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-rw-r--r--library/std/src/env.rs2
-rw-r--r--library/std/src/ffi/os_str.rs2
-rw-r--r--library/std/src/io/mod.rs4
-rw-r--r--library/std/src/keyword_docs.rs137
-rw-r--r--library/std/src/lib.rs15
-rw-r--r--library/std/src/net/hostname.rs22
-rw-r--r--library/std/src/net/mod.rs6
-rw-r--r--library/std/src/net/socket_addr.rs43
-rw-r--r--library/std/src/num/f128.rs16
-rw-r--r--library/std/src/num/f16.rs16
-rw-r--r--library/std/src/num/f32.rs19
-rw-r--r--library/std/src/num/f64.rs19
-rw-r--r--library/std/src/os/darwin/mod.rs2
-rw-r--r--library/std/src/os/darwin/objc.rs13
-rw-r--r--library/std/src/os/net/linux_ext/tcp.rs24
-rw-r--r--library/std/src/os/net/linux_ext/tests.rs11
-rw-r--r--library/std/src/os/unix/process.rs2
-rw-r--r--library/std/src/os/windows/ffi.rs2
-rw-r--r--library/std/src/panic.rs2
-rw-r--r--library/std/src/panicking.rs26
-rw-r--r--library/std/src/path.rs223
-rw-r--r--library/std/src/process.rs29
-rw-r--r--library/std/src/process/tests.rs102
-rw-r--r--library/std/src/rt.rs6
-rw-r--r--library/std/src/sync/nonpoison/condvar.rs9
-rw-r--r--library/std/src/sync/nonpoison/mutex.rs2
-rw-r--r--library/std/src/sync/nonpoison/rwlock.rs2
-rw-r--r--library/std/src/sync/poison/condvar.rs9
-rw-r--r--library/std/src/sync/poison/mutex.rs2
-rw-r--r--library/std/src/sync/poison/rwlock.rs2
-rw-r--r--library/std/src/sync/reentrant_lock.rs2
-rw-r--r--library/std/src/sys/alloc/mod.rs3
-rw-r--r--library/std/src/sys/alloc/vexos.rs96
-rw-r--r--library/std/src/sys/args/zkvm.rs103
-rw-r--r--library/std/src/sys/env_consts.rs13
-rw-r--r--library/std/src/sys/fs/mod.rs4
-rw-r--r--library/std/src/sys/fs/unix.rs120
-rw-r--r--library/std/src/sys/fs/vexos.rs615
-rw-r--r--library/std/src/sys/fs/wasi.rs9
-rw-r--r--library/std/src/sys/mod.rs1
-rw-r--r--library/std/src/sys/net/connection/sgx.rs29
-rw-r--r--library/std/src/sys/net/connection/socket/hermit.rs3
-rw-r--r--library/std/src/sys/net/connection/socket/mod.rs58
-rw-r--r--library/std/src/sys/net/connection/socket/tests.rs2
-rw-r--r--library/std/src/sys/net/connection/socket/unix.rs9
-rw-r--r--library/std/src/sys/net/connection/socket/windows.rs80
-rw-r--r--library/std/src/sys/net/connection/uefi/mod.rs22
-rw-r--r--library/std/src/sys/net/connection/unsupported.rs22
-rw-r--r--library/std/src/sys/net/connection/wasip1.rs22
-rw-r--r--library/std/src/sys/net/connection/xous/dns.rs45
-rw-r--r--library/std/src/sys/net/connection/xous/mod.rs2
-rw-r--r--library/std/src/sys/net/hostname/mod.rs14
-rw-r--r--library/std/src/sys/net/hostname/unix.rs62
-rw-r--r--library/std/src/sys/net/hostname/unsupported.rs6
-rw-r--r--library/std/src/sys/net/hostname/windows.rs24
-rw-r--r--library/std/src/sys/net/mod.rs3
-rw-r--r--library/std/src/sys/pal/hermit/mod.rs1
-rw-r--r--library/std/src/sys/pal/hermit/os.rs2
-rw-r--r--library/std/src/sys/pal/hermit/time.rs39
-rw-r--r--library/std/src/sys/pal/mod.rs4
-rw-r--r--library/std/src/sys/pal/sgx/abi/mod.rs2
-rw-r--r--library/std/src/sys/pal/sgx/mod.rs1
-rw-r--r--library/std/src/sys/pal/sgx/time.rs15
-rw-r--r--library/std/src/sys/pal/solid/mod.rs4
-rw-r--r--library/std/src/sys/pal/solid/time.rs9
-rw-r--r--library/std/src/sys/pal/teeos/mod.rs1
-rw-r--r--library/std/src/sys/pal/trusty/mod.rs2
-rw-r--r--library/std/src/sys/pal/uefi/helpers.rs4
-rw-r--r--library/std/src/sys/pal/uefi/mod.rs1
-rw-r--r--library/std/src/sys/pal/uefi/thread.rs66
-rw-r--r--library/std/src/sys/pal/uefi/time.rs27
-rw-r--r--library/std/src/sys/pal/unix/mod.rs3
-rw-r--r--library/std/src/sys/pal/unix/os.rs2
-rw-r--r--library/std/src/sys/pal/unix/stack_overflow.rs14
-rw-r--r--library/std/src/sys/pal/unix/time.rs53
-rw-r--r--library/std/src/sys/pal/unix/weak.rs130
-rw-r--r--library/std/src/sys/pal/unix/weak/tests.rs32
-rw-r--r--library/std/src/sys/pal/unsupported/mod.rs1
-rw-r--r--library/std/src/sys/pal/unsupported/time.rs15
-rw-r--r--library/std/src/sys/pal/vexos/mod.rs80
-rw-r--r--library/std/src/sys/pal/vexos/time.rs28
-rw-r--r--library/std/src/sys/pal/wasip1/mod.rs1
-rw-r--r--library/std/src/sys/pal/wasip1/thread.rs214
-rw-r--r--library/std/src/sys/pal/wasip1/time.rs25
-rw-r--r--library/std/src/sys/pal/wasip2/mod.rs1
-rw-r--r--library/std/src/sys/pal/wasip2/thread.rs73
-rw-r--r--library/std/src/sys/pal/wasip2/time.rs27
-rw-r--r--library/std/src/sys/pal/wasm/atomics/thread.rs75
-rw-r--r--library/std/src/sys/pal/wasm/mod.rs15
-rw-r--r--library/std/src/sys/pal/windows/c/bindings.txt2
-rw-r--r--library/std/src/sys/pal/windows/c/windows_sys.rs2
-rw-r--r--library/std/src/sys/pal/windows/mod.rs9
-rw-r--r--library/std/src/sys/pal/windows/time.rs32
-rw-r--r--library/std/src/sys/pal/windows/winsock.rs80
-rw-r--r--library/std/src/sys/pal/xous/mod.rs1
-rw-r--r--library/std/src/sys/pal/xous/time.rs15
-rw-r--r--library/std/src/sys/pal/zkvm/mod.rs2
-rw-r--r--library/std/src/sys/process/mod.rs2
-rw-r--r--library/std/src/sys/process/uefi.rs9
-rw-r--r--library/std/src/sys/process/unix/common.rs9
-rw-r--r--library/std/src/sys/process/unix/fuchsia.rs1
-rw-r--r--library/std/src/sys/process/unix/mod.rs2
-rw-r--r--library/std/src/sys/process/unix/unix.rs1
-rw-r--r--library/std/src/sys/process/unix/unix/tests.rs1
-rw-r--r--library/std/src/sys/process/unix/unsupported.rs1
-rw-r--r--library/std/src/sys/process/unix/vxworks.rs4
-rw-r--r--library/std/src/sys/process/unsupported.rs9
-rw-r--r--library/std/src/sys/process/windows.rs7
-rw-r--r--library/std/src/sys/random/mod.rs2
-rw-r--r--library/std/src/sys/stdio/mod.rs4
-rw-r--r--library/std/src/sys/stdio/vexos.rs100
-rw-r--r--library/std/src/sys/sync/once/queue.rs4
-rw-r--r--library/std/src/sys/thread/hermit.rs (renamed from library/std/src/sys/pal/hermit/thread.rs)66
-rw-r--r--library/std/src/sys/thread/mod.rs159
-rw-r--r--library/std/src/sys/thread/sgx.rs (renamed from library/std/src/sys/pal/sgx/thread.rs)49
-rw-r--r--library/std/src/sys/thread/solid.rs (renamed from library/std/src/sys/pal/itron/thread.rs)42
-rw-r--r--library/std/src/sys/thread/teeos.rs (renamed from library/std/src/sys/pal/teeos/thread.rs)71
-rw-r--r--library/std/src/sys/thread/uefi.rs25
-rw-r--r--library/std/src/sys/thread/unix.rs (renamed from library/std/src/sys/pal/unix/thread.rs)667
-rw-r--r--library/std/src/sys/thread/unsupported.rs (renamed from library/std/src/sys/pal/unsupported/thread.rs)39
-rw-r--r--library/std/src/sys/thread/vexos.rs17
-rw-r--r--library/std/src/sys/thread/wasip1.rs185
-rw-r--r--library/std/src/sys/thread/wasip2.rs32
-rw-r--r--library/std/src/sys/thread/wasm.rs23
-rw-r--r--library/std/src/sys/thread/windows.rs (renamed from library/std/src/sys/pal/windows/thread.rs)112
-rw-r--r--library/std/src/sys/thread/xous.rs (renamed from library/std/src/sys/pal/xous/thread.rs)54
-rw-r--r--library/std/src/sys/thread_local/mod.rs4
-rw-r--r--library/std/src/sys/thread_local/native/eager.rs4
-rw-r--r--library/std/src/sys/thread_local/native/lazy.rs4
-rw-r--r--library/std/src/sys/thread_local/native/mod.rs12
-rw-r--r--library/std/src/sys/thread_local/no_threads.rs69
-rw-r--r--library/std/src/sys/thread_local/os.rs155
-rw-r--r--library/std/src/thread/current.rs24
-rw-r--r--library/std/src/thread/local.rs235
-rw-r--r--library/std/src/thread/mod.rs80
-rw-r--r--library/std/src/thread/tests.rs4
-rw-r--r--library/std/src/time.rs30
137 files changed, 3565 insertions, 2001 deletions
diff --git a/library/std/src/env.rs b/library/std/src/env.rs
index e457cd61c75..6d716bd8544 100644
--- a/library/std/src/env.rs
+++ b/library/std/src/env.rs
@@ -1098,6 +1098,7 @@ pub mod consts {
     /// * `"redox"`
     /// * `"solaris"`
     /// * `"solid_asp3`
+    /// * `"vexos"`
     /// * `"vita"`
     /// * `"vxworks"`
     /// * `"xous"`
@@ -1148,6 +1149,7 @@ pub mod consts {
     ///
     /// <details><summary>Full list of possible values</summary>
     ///
+    /// * `"bin"`
     /// * `"exe"`
     /// * `"efi"`
     /// * `"js"`
diff --git a/library/std/src/ffi/os_str.rs b/library/std/src/ffi/os_str.rs
index a39565d2159..6c098034eea 100644
--- a/library/std/src/ffi/os_str.rs
+++ b/library/std/src/ffi/os_str.rs
@@ -137,7 +137,7 @@ impl OsString {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     #[inline]
-    #[rustc_const_stable(feature = "const_pathbuf_osstring_new", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_pathbuf_osstring_new", since = "1.91.0")]
     pub const fn new() -> OsString {
         OsString { inner: Buf::from_string(String::new()) }
     }
diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs
index ff0e29e04c2..25a4661a0bc 100644
--- a/library/std/src/io/mod.rs
+++ b/library/std/src/io/mod.rs
@@ -1081,7 +1081,7 @@ pub trait Read {
         default_read_buf_exact(self, cursor)
     }
 
-    /// Creates a "by reference" adaptor for this instance of `Read`.
+    /// Creates a "by reference" adapter for this instance of `Read`.
     ///
     /// The returned adapter also implements `Read` and will simply borrow this
     /// current reader.
@@ -3234,7 +3234,7 @@ fn inlined_slow_read_byte<R: Read>(reader: &mut R) -> Option<Result<u8>> {
     }
 }
 
-// Used by `BufReader::spec_read_byte`, for which the `inline(ever)` is
+// Used by `BufReader::spec_read_byte`, for which the `inline(never)` is
 // important.
 #[inline(never)]
 fn uninlined_slow_read_byte<R: Read>(reader: &mut R) -> Option<Result<u8>> {
diff --git a/library/std/src/keyword_docs.rs b/library/std/src/keyword_docs.rs
index 1c55824ab90..dc0d11b07a9 100644
--- a/library/std/src/keyword_docs.rs
+++ b/library/std/src/keyword_docs.rs
@@ -1,6 +1,8 @@
 #[doc(keyword = "as")]
 //
-/// Cast between types, or rename an import.
+/// Cast between types, rename an import, or qualify paths to associated items.
+///
+/// # Type casting
 ///
 /// `as` is most commonly used to turn primitive types into other primitive types, but it has other
 /// uses that include turning pointers into addresses, addresses into pointers, and pointers into
@@ -30,6 +32,8 @@
 /// `as *mut _` though the [`cast`][const-cast] method is recommended over `as *const _` and it is
 /// [the same][mut-cast] for `as *mut _`: those methods make the intent clearer.
 ///
+/// # Renaming imports
+///
 /// `as` is also used to rename imports in [`use`] and [`extern crate`][`crate`] statements:
 ///
 /// ```
@@ -37,9 +41,34 @@
 /// use std::{mem as memory, net as network};
 /// // Now you can use the names `memory` and `network` to refer to `std::mem` and `std::net`.
 /// ```
-/// For more information on what `as` is capable of, see the [Reference].
 ///
-/// [Reference]: ../reference/expressions/operator-expr.html#type-cast-expressions
+/// # Qualifying paths
+///
+/// You'll also find with `From` and `Into`, and indeed all traits, that `as` is used for the
+/// _fully qualified path_, a means of disambiguating associated items, i.e. functions,
+/// constants, and types.  For example, if you have a type which implements two traits with identical
+/// method names (e.g. `Into::<u32>::into` and `Into::<u64>::into`), you can clarify which method
+/// you'll use with `<MyThing as Into<u32>>::into(my_thing)`[^as-use-from].  This is quite verbose,
+/// but fortunately, Rust's type inference usually saves you from needing this, although it is
+/// occasionally necessary, especially with methods that return a generic type like `Into::into` or
+/// methods that don't take `self`.  It's more common to use in macros where it can provide necessary
+/// hygiene.
+///
+/// [^as-use-from]: You should probably never use this syntax with `Into` and instead write
+/// `T::from(my_thing)`.  It just happens that there aren't any great examples for this syntax in
+/// the standard library.  Also, at time of writing, the compiler tends to suggest fully-qualified
+/// paths to fix ambiguous `Into::into` calls, so the example should hopefully be familiar.
+///
+/// # Further reading
+///
+/// For more information on what `as` is capable of, see the Reference on [type cast expressions],
+/// [renaming imported entities], [renaming `extern` crates]
+/// and [qualified paths].
+///
+/// [type cast expressions]: ../reference/expressions/operator-expr.html#type-cast-expressions
+/// [renaming imported entities]: https://doc.rust-lang.org/reference/items/use-declarations.html#as-renames
+/// [renaming `extern` crates]: https://doc.rust-lang.org/reference/items/extern-crates.html#r-items.extern-crate.as
+/// [qualified paths]: ../reference/paths.html#qualified-paths
 /// [`crate`]: keyword.crate.html
 /// [`use`]: keyword.use.html
 /// [const-cast]: pointer::cast
@@ -1257,6 +1286,108 @@ mod ref_keyword {}
 /// [`async`]: ../std/keyword.async.html
 mod return_keyword {}
 
+#[doc(keyword = "become")]
+//
+/// Perform a tail-call of a function.
+///
+/// <div class="warning">
+///
+/// `feature(explicit_tail_calls)` is currently incomplete and may not work properly.
+/// </div>
+///
+/// When tail calling a function, instead of its stack frame being added to the
+/// stack, the stack frame of the caller is directly replaced with the callee's.
+/// This means that as long as a loop in a call graph only uses tail calls, the
+/// stack growth will be bounded.
+///
+/// This is useful for writing functional-style code (since it prevents recursion
+/// from exhausting resources) or for code optimization (since a tail call
+/// *might* be cheaper than a normal call, tail calls can be used in a similar
+/// manner to computed goto).
+///
+/// Example of using `become` to implement functional-style `fold`:
+/// ```
+/// #![feature(explicit_tail_calls)]
+/// #![expect(incomplete_features)]
+///
+/// fn fold<T: Copy, S>(slice: &[T], init: S, f: impl Fn(S, T) -> S) -> S {
+///     match slice {
+///         // without `become`, on big inputs this could easily overflow the
+///         // stack. using a tail call guarantees that the stack will not grow unboundedly
+///         [first, rest @ ..] => become fold(rest, f(init, *first), f),
+///         [] => init,
+///     }
+/// }
+/// ```
+///
+/// Compilers can already perform "tail call optimization" -- they can replace normal
+/// calls with tail calls, although there are no guarantees that this will be done.
+/// However, to perform TCO, the call needs to be the last thing that happens
+/// in the functions and be returned from it. This requirement is often broken
+/// by drop code for locals, which is run after computing the return expression:
+///
+/// ```
+/// fn example() {
+///     let string = "meow".to_owned();
+///     println!("{string}");
+///     return help(); // this is *not* the last thing that happens in `example`...
+/// }
+///
+/// // ... because it is desugared to this:
+/// fn example_desugared() {
+///     let string = "meow".to_owned();
+///     println!("{string}");
+///     let tmp = help();
+///     drop(string);
+///     return tmp;
+/// }
+///
+/// fn help() {}
+/// ```
+///
+/// For this reason, `become` also changes the drop order, such that locals are
+/// dropped *before* evaluating the call.
+///
+/// In order to guarantee that the compiler can perform a tail call, `become`
+/// currently has these requirements:
+/// 1. callee and caller must have the same ABI, arguments, and return type
+/// 2. callee and caller must not have varargs
+/// 3. caller must not be marked with `#[track_caller]`
+///    - callee is allowed to be marked with `#[track_caller]` as otherwise
+///      adding `#[track_caller]` would be a breaking change. if callee is
+///      marked with `#[track_caller]` a tail call is not guaranteed.
+/// 4. callee and caller cannot be a closure
+///    (unless it's coerced to a function pointer)
+///
+/// It is possible to tail-call a function pointer:
+/// ```
+/// #![feature(explicit_tail_calls)]
+/// #![expect(incomplete_features)]
+///
+/// #[derive(Copy, Clone)]
+/// enum Inst { Inc, Dec }
+///
+/// fn dispatch(stream: &[Inst], state: u32) -> u32 {
+///     const TABLE: &[fn(&[Inst], u32) -> u32] = &[increment, decrement];
+///     match stream {
+///         [inst, rest @ ..] => become TABLE[*inst as usize](rest, state),
+///         [] => state,
+///     }
+/// }
+///
+/// fn increment(stream: &[Inst], state: u32) -> u32 {
+///     become dispatch(stream, state + 1)
+/// }
+///
+/// fn decrement(stream: &[Inst], state: u32) -> u32 {
+///     become dispatch(stream, state - 1)
+/// }
+///
+/// let program = &[Inst::Inc, Inst::Inc, Inst::Dec, Inst::Inc];
+/// assert_eq!(dispatch(program, 0), 2);
+/// ```
+mod become_keyword {}
+
 #[doc(keyword = "self")]
 //
 /// The receiver of a method, or the current module.
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 97db0d6ab75..da41c1216c4 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -94,7 +94,7 @@
 //! pull-requests for your suggested changes.
 //!
 //! Contributions are appreciated! If you see a part of the docs that can be
-//! improved, submit a PR, or chat with us first on [Discord][rust-discord]
+//! improved, submit a PR, or chat with us first on [Zulip][rust-zulip]
 //! #docs.
 //!
 //! # A Tour of The Rust Standard Library
@@ -212,7 +212,7 @@
 //! [multithreading]: thread
 //! [other]: #what-is-in-the-standard-library-documentation
 //! [primitive types]: ../book/ch03-02-data-types.html
-//! [rust-discord]: https://discord.gg/rust-lang
+//! [rust-zulip]: https://rust-lang.zulipchat.com/
 //! [array]: prim@array
 //! [slice]: prim@slice
 
@@ -235,7 +235,7 @@
     test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
 )]
 #![doc(rust_logo)]
-#![doc(cfg_hide(not(test), no_global_oom_handling, not(no_global_oom_handling)))]
+#![doc(auto_cfg(hide(no_global_oom_handling)))]
 // Don't link to std. We are std.
 #![no_std]
 // Tell the compiler to link to either panic_abort or panic_unwind
@@ -284,9 +284,7 @@
 #![feature(core_float_math)]
 #![feature(decl_macro)]
 #![feature(deprecated_suggestion)]
-#![feature(derive_const)]
 #![feature(doc_cfg)]
-#![feature(doc_cfg_hide)]
 #![feature(doc_masked)]
 #![feature(doc_notable_trait)]
 #![feature(dropck_eyepatch)]
@@ -332,11 +330,8 @@
 #![feature(cfg_select)]
 #![feature(char_internals)]
 #![feature(clone_to_uninit)]
-#![feature(const_cmp)]
 #![feature(const_convert)]
-#![feature(const_ops)]
-#![feature(const_option_ops)]
-#![feature(const_try)]
+#![feature(const_mul_add)]
 #![feature(core_intrinsics)]
 #![feature(core_io_borrowed_buf)]
 #![feature(drop_guard)]
@@ -350,6 +345,7 @@
 #![feature(float_gamma)]
 #![feature(float_minimum_maximum)]
 #![feature(fmt_internals)]
+#![feature(fn_ptr_trait)]
 #![feature(generic_atomic)]
 #![feature(hasher_prefixfree_extras)]
 #![feature(hashmap_internals)]
@@ -385,7 +381,6 @@
 #![feature(allocator_api)]
 #![feature(get_mut_unchecked)]
 #![feature(map_try_insert)]
-#![feature(new_zeroed_alloc)]
 #![feature(slice_concat_trait)]
 #![feature(thin_box)]
 #![feature(try_reserve_kind)]
diff --git a/library/std/src/net/hostname.rs b/library/std/src/net/hostname.rs
new file mode 100644
index 00000000000..b1010cec600
--- /dev/null
+++ b/library/std/src/net/hostname.rs
@@ -0,0 +1,22 @@
+use crate::ffi::OsString;
+
+/// Returns the system hostname.
+///
+/// This can error out in platform-specific error cases;
+/// for example, uefi and wasm, where hostnames aren't
+/// supported.
+///
+/// # Underlying system calls
+///
+/// | Platform | System call                                                                                             |
+/// |----------|---------------------------------------------------------------------------------------------------------|
+/// | UNIX     | [`gethostname`](https://www.man7.org/linux/man-pages/man2/gethostname.2.html)                           |
+/// | Windows  | [`GetHostNameW`](https://learn.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-gethostnamew) |
+///
+/// Note that platform-specific behavior [may change in the future][changes].
+///
+/// [changes]: crate::io#platform-specific-behavior
+#[unstable(feature = "gethostname", issue = "135142")]
+pub fn hostname() -> crate::io::Result<OsString> {
+    crate::sys::net::hostname()
+}
diff --git a/library/std/src/net/mod.rs b/library/std/src/net/mod.rs
index 40f1a93e39d..3e4447eb33f 100644
--- a/library/std/src/net/mod.rs
+++ b/library/std/src/net/mod.rs
@@ -1,7 +1,8 @@
 //! Networking primitives for TCP/UDP communication.
 //!
 //! This module provides networking functionality for the Transmission Control and User
-//! Datagram Protocols, as well as types for IP and socket addresses.
+//! Datagram Protocols, as well as types for IP and socket addresses and functions related
+//! to network properties.
 //!
 //! # Organization
 //!
@@ -24,6 +25,8 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::net::AddrParseError;
 
+#[unstable(feature = "gethostname", issue = "135142")]
+pub use self::hostname::hostname;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::ip_addr::{IpAddr, Ipv4Addr, Ipv6Addr, Ipv6MulticastScope};
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -35,6 +38,7 @@ pub use self::tcp::{Incoming, TcpListener, TcpStream};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::udp::UdpSocket;
 
+mod hostname;
 mod ip_addr;
 mod socket_addr;
 mod tcp;
diff --git a/library/std/src/net/socket_addr.rs b/library/std/src/net/socket_addr.rs
index 41e623e79ce..8214ad381f1 100644
--- a/library/std/src/net/socket_addr.rs
+++ b/library/std/src/net/socket_addr.rs
@@ -6,7 +6,6 @@ mod tests;
 pub use core::net::{SocketAddr, SocketAddrV4, SocketAddrV6};
 
 use crate::net::{IpAddr, Ipv4Addr, Ipv6Addr};
-use crate::sys::net::LookupHost;
 use crate::{io, iter, option, slice, vec};
 
 /// A trait for objects which can be converted or resolved to one or more
@@ -29,6 +28,8 @@ use crate::{io, iter, option, slice, vec};
 ///    [`SocketAddr`] as expected by its [`FromStr`] implementation or a string like
 ///    `<host_name>:<port>` pair where `<port>` is a [`u16`] value.
 ///
+///  * <code>&[[SocketAddr]]</code>: all [`SocketAddr`] values in the slice will be used.
+///
 /// This trait allows constructing network objects like [`TcpStream`] or
 /// [`UdpSocket`] easily with values of various types for the bind/connection
 /// address. It is needed because sometimes one type is more appropriate than
@@ -188,15 +189,9 @@ impl ToSocketAddrs for (Ipv6Addr, u16) {
     }
 }
 
-fn resolve_socket_addr(lh: LookupHost) -> io::Result<vec::IntoIter<SocketAddr>> {
-    let p = lh.port();
-    let v: Vec<_> = lh
-        .map(|mut a| {
-            a.set_port(p);
-            a
-        })
-        .collect();
-    Ok(v.into_iter())
+fn lookup_host(host: &str, port: u16) -> io::Result<vec::IntoIter<SocketAddr>> {
+    let addrs = crate::sys::net::lookup_host(host, port)?;
+    Ok(Vec::from_iter(addrs).into_iter())
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -205,17 +200,14 @@ impl ToSocketAddrs for (&str, u16) {
     fn to_socket_addrs(&self) -> io::Result<vec::IntoIter<SocketAddr>> {
         let (host, port) = *self;
 
-        // try to parse the host as a regular IP address first
-        if let Ok(addr) = host.parse::<Ipv4Addr>() {
-            let addr = SocketAddrV4::new(addr, port);
-            return Ok(vec![SocketAddr::V4(addr)].into_iter());
-        }
-        if let Ok(addr) = host.parse::<Ipv6Addr>() {
-            let addr = SocketAddrV6::new(addr, port, 0, 0);
-            return Ok(vec![SocketAddr::V6(addr)].into_iter());
+        // Try to parse the host as a regular IP address first
+        if let Ok(addr) = host.parse::<IpAddr>() {
+            let addr = SocketAddr::new(addr, port);
+            return Ok(vec![addr].into_iter());
         }
 
-        resolve_socket_addr((host, port).try_into()?)
+        // Otherwise, make the system look it up.
+        lookup_host(host, port)
     }
 }
 
@@ -232,12 +224,21 @@ impl ToSocketAddrs for (String, u16) {
 impl ToSocketAddrs for str {
     type Iter = vec::IntoIter<SocketAddr>;
     fn to_socket_addrs(&self) -> io::Result<vec::IntoIter<SocketAddr>> {
-        // try to parse as a regular SocketAddr first
+        // Try to parse as a regular SocketAddr first
         if let Ok(addr) = self.parse() {
             return Ok(vec![addr].into_iter());
         }
 
-        resolve_socket_addr(self.try_into()?)
+        // Otherwise, split the string by ':' and convert the second part to u16...
+        let Some((host, port_str)) = self.rsplit_once(':') else {
+            return Err(io::const_error!(io::ErrorKind::InvalidInput, "invalid socket address"));
+        };
+        let Ok(port) = port_str.parse::<u16>() else {
+            return Err(io::const_error!(io::ErrorKind::InvalidInput, "invalid port value"));
+        };
+
+        // ... and make the system look up the host.
+        lookup_host(host, port)
     }
 }
 
diff --git a/library/std/src/num/f128.rs b/library/std/src/num/f128.rs
index 5a85c1daaf0..40061d08928 100644
--- a/library/std/src/num/f128.rs
+++ b/library/std/src/num/f128.rs
@@ -44,7 +44,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn powf(self, n: f128) -> f128 {
-        unsafe { intrinsics::powf128(self, n) }
+        intrinsics::powf128(self, n)
     }
 
     /// Returns `e^(self)`, (the exponential function).
@@ -76,7 +76,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn exp(self) -> f128 {
-        unsafe { intrinsics::expf128(self) }
+        intrinsics::expf128(self)
     }
 
     /// Returns `2^(self)`.
@@ -106,7 +106,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn exp2(self) -> f128 {
-        unsafe { intrinsics::exp2f128(self) }
+        intrinsics::exp2f128(self)
     }
 
     /// Returns the natural logarithm of the number.
@@ -151,7 +151,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn ln(self) -> f128 {
-        unsafe { intrinsics::logf128(self) }
+        intrinsics::logf128(self)
     }
 
     /// Returns the logarithm of the number with respect to an arbitrary base.
@@ -241,7 +241,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn log2(self) -> f128 {
-        unsafe { intrinsics::log2f128(self) }
+        intrinsics::log2f128(self)
     }
 
     /// Returns the base 10 logarithm of the number.
@@ -284,7 +284,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn log10(self) -> f128 {
-        unsafe { intrinsics::log10f128(self) }
+        intrinsics::log10f128(self)
     }
 
     /// Returns the cube root of a number.
@@ -385,7 +385,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn sin(self) -> f128 {
-        unsafe { intrinsics::sinf128(self) }
+        intrinsics::sinf128(self)
     }
 
     /// Computes the cosine of a number (in radians).
@@ -414,7 +414,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn cos(self) -> f128 {
-        unsafe { intrinsics::cosf128(self) }
+        intrinsics::cosf128(self)
     }
 
     /// Computes the tangent of a number (in radians).
diff --git a/library/std/src/num/f16.rs b/library/std/src/num/f16.rs
index cc10c41b9e7..0d43b60a62f 100644
--- a/library/std/src/num/f16.rs
+++ b/library/std/src/num/f16.rs
@@ -44,7 +44,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn powf(self, n: f16) -> f16 {
-        unsafe { intrinsics::powf16(self, n) }
+        intrinsics::powf16(self, n)
     }
 
     /// Returns `e^(self)`, (the exponential function).
@@ -76,7 +76,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn exp(self) -> f16 {
-        unsafe { intrinsics::expf16(self) }
+        intrinsics::expf16(self)
     }
 
     /// Returns `2^(self)`.
@@ -106,7 +106,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn exp2(self) -> f16 {
-        unsafe { intrinsics::exp2f16(self) }
+        intrinsics::exp2f16(self)
     }
 
     /// Returns the natural logarithm of the number.
@@ -151,7 +151,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn ln(self) -> f16 {
-        unsafe { intrinsics::logf16(self) }
+        intrinsics::logf16(self)
     }
 
     /// Returns the logarithm of the number with respect to an arbitrary base.
@@ -241,7 +241,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn log2(self) -> f16 {
-        unsafe { intrinsics::log2f16(self) }
+        intrinsics::log2f16(self)
     }
 
     /// Returns the base 10 logarithm of the number.
@@ -284,7 +284,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn log10(self) -> f16 {
-        unsafe { intrinsics::log10f16(self) }
+        intrinsics::log10f16(self)
     }
 
     /// Compute the distance between the origin and a point (`x`, `y`) on the
@@ -350,7 +350,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn sin(self) -> f16 {
-        unsafe { intrinsics::sinf16(self) }
+        intrinsics::sinf16(self)
     }
 
     /// Computes the cosine of a number (in radians).
@@ -379,7 +379,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn cos(self) -> f16 {
-        unsafe { intrinsics::cosf16(self) }
+        intrinsics::cosf16(self)
     }
 
     /// Computes the tangent of a number (in radians).
diff --git a/library/std/src/num/f32.rs b/library/std/src/num/f32.rs
index 72e5f4d4c41..c9e192201af 100644
--- a/library/std/src/num/f32.rs
+++ b/library/std/src/num/f32.rs
@@ -217,7 +217,8 @@ impl f32 {
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn mul_add(self, a: f32, b: f32) -> f32 {
+    #[rustc_const_unstable(feature = "const_mul_add", issue = "146724")]
+    pub const fn mul_add(self, a: f32, b: f32) -> f32 {
         core::f32::math::mul_add(self, a, b)
     }
 
@@ -338,7 +339,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn powf(self, n: f32) -> f32 {
-        unsafe { intrinsics::powf32(self, n) }
+        intrinsics::powf32(self, n)
     }
 
     /// Returns the square root of a number.
@@ -395,7 +396,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn exp(self) -> f32 {
-        unsafe { intrinsics::expf32(self) }
+        intrinsics::expf32(self)
     }
 
     /// Returns `2^(self)`.
@@ -420,7 +421,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn exp2(self) -> f32 {
-        unsafe { intrinsics::exp2f32(self) }
+        intrinsics::exp2f32(self)
     }
 
     /// Returns the natural logarithm of the number.
@@ -455,7 +456,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn ln(self) -> f32 {
-        unsafe { intrinsics::logf32(self) }
+        intrinsics::logf32(self)
     }
 
     /// Returns the logarithm of the number with respect to an arbitrary base.
@@ -525,7 +526,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn log2(self) -> f32 {
-        unsafe { intrinsics::log2f32(self) }
+        intrinsics::log2f32(self)
     }
 
     /// Returns the base 10 logarithm of the number.
@@ -558,7 +559,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn log10(self) -> f32 {
-        unsafe { intrinsics::log10f32(self) }
+        intrinsics::log10f32(self)
     }
 
     /// The positive difference of two numbers.
@@ -683,7 +684,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn sin(self) -> f32 {
-        unsafe { intrinsics::sinf32(self) }
+        intrinsics::sinf32(self)
     }
 
     /// Computes the cosine of a number (in radians).
@@ -707,7 +708,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn cos(self) -> f32 {
-        unsafe { intrinsics::cosf32(self) }
+        intrinsics::cosf32(self)
     }
 
     /// Computes the tangent of a number (in radians).
diff --git a/library/std/src/num/f64.rs b/library/std/src/num/f64.rs
index 5f3e793c3a7..11874f9280f 100644
--- a/library/std/src/num/f64.rs
+++ b/library/std/src/num/f64.rs
@@ -217,7 +217,8 @@ impl f64 {
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn mul_add(self, a: f64, b: f64) -> f64 {
+    #[rustc_const_unstable(feature = "const_mul_add", issue = "146724")]
+    pub const fn mul_add(self, a: f64, b: f64) -> f64 {
         core::f64::math::mul_add(self, a, b)
     }
 
@@ -338,7 +339,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn powf(self, n: f64) -> f64 {
-        unsafe { intrinsics::powf64(self, n) }
+        intrinsics::powf64(self, n)
     }
 
     /// Returns the square root of a number.
@@ -395,7 +396,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn exp(self) -> f64 {
-        unsafe { intrinsics::expf64(self) }
+        intrinsics::expf64(self)
     }
 
     /// Returns `2^(self)`.
@@ -420,7 +421,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn exp2(self) -> f64 {
-        unsafe { intrinsics::exp2f64(self) }
+        intrinsics::exp2f64(self)
     }
 
     /// Returns the natural logarithm of the number.
@@ -455,7 +456,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn ln(self) -> f64 {
-        unsafe { intrinsics::logf64(self) }
+        intrinsics::logf64(self)
     }
 
     /// Returns the logarithm of the number with respect to an arbitrary base.
@@ -525,7 +526,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn log2(self) -> f64 {
-        unsafe { intrinsics::log2f64(self) }
+        intrinsics::log2f64(self)
     }
 
     /// Returns the base 10 logarithm of the number.
@@ -558,7 +559,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn log10(self) -> f64 {
-        unsafe { intrinsics::log10f64(self) }
+        intrinsics::log10f64(self)
     }
 
     /// The positive difference of two numbers.
@@ -683,7 +684,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn sin(self) -> f64 {
-        unsafe { intrinsics::sinf64(self) }
+        intrinsics::sinf64(self)
     }
 
     /// Computes the cosine of a number (in radians).
@@ -707,7 +708,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn cos(self) -> f64 {
-        unsafe { intrinsics::cosf64(self) }
+        intrinsics::cosf64(self)
     }
 
     /// Computes the tangent of a number (in radians).
diff --git a/library/std/src/os/darwin/mod.rs b/library/std/src/os/darwin/mod.rs
index 3b1bd974fa3..ff184f477fb 100644
--- a/library/std/src/os/darwin/mod.rs
+++ b/library/std/src/os/darwin/mod.rs
@@ -17,6 +17,8 @@
 #![doc(cfg(target_vendor = "apple"))]
 
 pub mod fs;
+pub mod objc;
+
 // deprecated, but used for public reexport under `std::os::unix::raw`, as
 // well as `std::os::macos`/`std::os::ios`, because those modules precede the
 // decision to remove these.
diff --git a/library/std/src/os/darwin/objc.rs b/library/std/src/os/darwin/objc.rs
new file mode 100644
index 00000000000..a4b31fee7c5
--- /dev/null
+++ b/library/std/src/os/darwin/objc.rs
@@ -0,0 +1,13 @@
+//! Defines types and macros for Objective-C interoperability.
+//!
+//! This module re-exports all the items in [`core::os::darwin::objc`].
+//!
+//! [`core::os::darwin::objc`]: ../../../../core/os/darwin/objc/index.html "mod core::os::darwin::objc"
+
+#![unstable(feature = "darwin_objc", issue = "145496")]
+
+// We can't generate an intra-doc link for this automatically since `core::os::darwin` isn't
+// compiled into `core` on every platform even though it's documented on every platform.
+// We just link to it directly in the module documentation above instead.
+#[cfg(not(doc))]
+pub use core::os::darwin::objc::*;
diff --git a/library/std/src/os/net/linux_ext/tcp.rs b/library/std/src/os/net/linux_ext/tcp.rs
index fde53ec4257..3f9b2bd3f4b 100644
--- a/library/std/src/os/net/linux_ext/tcp.rs
+++ b/library/std/src/os/net/linux_ext/tcp.rs
@@ -4,6 +4,8 @@
 
 use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
+#[cfg(target_os = "linux")]
+use crate::time::Duration;
 use crate::{io, net};
 
 /// Os-specific extensions for [`TcpStream`]
@@ -59,11 +61,13 @@ pub trait TcpStreamExt: Sealed {
 
     /// A socket listener will be awakened solely when data arrives.
     ///
-    /// The `accept` argument set the delay in seconds until the
+    /// The `accept` argument set the maximum delay until the
     /// data is available to read, reducing the number of short lived
     /// connections without data to process.
     /// Contrary to other platforms `SO_ACCEPTFILTER` feature equivalent, there is
     /// no necessity to set it after the `listen` call.
+    /// Note that the delay is expressed as Duration from user's perspective
+    /// the call rounds it down to the nearest second expressible as a `c_int`.
     ///
     /// See [`man 7 tcp`](https://man7.org/linux/man-pages/man7/tcp.7.html)
     ///
@@ -73,16 +77,17 @@ pub trait TcpStreamExt: Sealed {
     /// #![feature(tcp_deferaccept)]
     /// use std::net::TcpStream;
     /// use std::os::linux::net::TcpStreamExt;
+    /// use std::time::Duration;
     ///
     /// let stream = TcpStream::connect("127.0.0.1:8080")
     ///         .expect("Couldn't connect to the server...");
-    /// stream.set_deferaccept(1).expect("set_deferaccept call failed");
+    /// stream.set_deferaccept(Duration::from_secs(1u64)).expect("set_deferaccept call failed");
     /// ```
     #[unstable(feature = "tcp_deferaccept", issue = "119639")]
     #[cfg(target_os = "linux")]
-    fn set_deferaccept(&self, accept: u32) -> io::Result<()>;
+    fn set_deferaccept(&self, accept: Duration) -> io::Result<()>;
 
-    /// Gets the accept delay value (in seconds) of the `TCP_DEFER_ACCEPT` option.
+    /// Gets the accept delay value of the `TCP_DEFER_ACCEPT` option.
     ///
     /// For more information about this option, see [`TcpStreamExt::set_deferaccept`].
     ///
@@ -92,15 +97,16 @@ pub trait TcpStreamExt: Sealed {
     /// #![feature(tcp_deferaccept)]
     /// use std::net::TcpStream;
     /// use std::os::linux::net::TcpStreamExt;
+    /// use std::time::Duration;
     ///
     /// let stream = TcpStream::connect("127.0.0.1:8080")
     ///         .expect("Couldn't connect to the server...");
-    /// stream.set_deferaccept(1).expect("set_deferaccept call failed");
-    /// assert_eq!(stream.deferaccept().unwrap_or(0), 1);
+    /// stream.set_deferaccept(Duration::from_secs(1u64)).expect("set_deferaccept call failed");
+    /// assert_eq!(stream.deferaccept().unwrap(), Duration::from_secs(1u64));
     /// ```
     #[unstable(feature = "tcp_deferaccept", issue = "119639")]
     #[cfg(target_os = "linux")]
-    fn deferaccept(&self) -> io::Result<u32>;
+    fn deferaccept(&self) -> io::Result<Duration>;
 }
 
 #[stable(feature = "tcp_quickack", since = "1.89.0")]
@@ -117,12 +123,12 @@ impl TcpStreamExt for net::TcpStream {
     }
 
     #[cfg(target_os = "linux")]
-    fn set_deferaccept(&self, accept: u32) -> io::Result<()> {
+    fn set_deferaccept(&self, accept: Duration) -> io::Result<()> {
         self.as_inner().as_inner().set_deferaccept(accept)
     }
 
     #[cfg(target_os = "linux")]
-    fn deferaccept(&self) -> io::Result<u32> {
+    fn deferaccept(&self) -> io::Result<Duration> {
         self.as_inner().as_inner().deferaccept()
     }
 }
diff --git a/library/std/src/os/net/linux_ext/tests.rs b/library/std/src/os/net/linux_ext/tests.rs
index 12f35696abc..0758b426ccc 100644
--- a/library/std/src/os/net/linux_ext/tests.rs
+++ b/library/std/src/os/net/linux_ext/tests.rs
@@ -32,6 +32,7 @@ fn deferaccept() {
     use crate::net::test::next_test_ip4;
     use crate::net::{TcpListener, TcpStream};
     use crate::os::net::linux_ext::tcp::TcpStreamExt;
+    use crate::time::Duration;
 
     macro_rules! t {
         ($e:expr) => {
@@ -43,10 +44,12 @@ fn deferaccept() {
     }
 
     let addr = next_test_ip4();
+    let one = Duration::from_secs(1u64);
+    let zero = Duration::from_secs(0u64);
     let _listener = t!(TcpListener::bind(&addr));
     let stream = t!(TcpStream::connect(&("localhost", addr.port())));
-    stream.set_deferaccept(1).expect("set_deferaccept failed");
-    assert_eq!(stream.deferaccept().unwrap(), 1);
-    stream.set_deferaccept(0).expect("set_deferaccept failed");
-    assert_eq!(stream.deferaccept().unwrap(), 0);
+    stream.set_deferaccept(one).expect("set_deferaccept failed");
+    assert_eq!(stream.deferaccept().unwrap(), one);
+    stream.set_deferaccept(zero).expect("set_deferaccept failed");
+    assert_eq!(stream.deferaccept().unwrap(), zero);
 }
diff --git a/library/std/src/os/unix/process.rs b/library/std/src/os/unix/process.rs
index 09429af06e3..5b7b5a8ea80 100644
--- a/library/std/src/os/unix/process.rs
+++ b/library/std/src/os/unix/process.rs
@@ -406,8 +406,10 @@ pub trait ChildExt: Sealed {
     /// use libc::SIGTERM;
     ///
     /// fn main() -> io::Result<()> {
+    ///     # if cfg!(not(all(target_vendor = "apple", not(target_os = "macos")))) {
     ///     let child = Command::new("cat").stdin(Stdio::piped()).spawn()?;
     ///     child.send_signal(SIGTERM)?;
+    ///     # }
     ///     Ok(())
     /// }
     /// ```
diff --git a/library/std/src/os/windows/ffi.rs b/library/std/src/os/windows/ffi.rs
index 345d5b74285..20e5383dc09 100644
--- a/library/std/src/os/windows/ffi.rs
+++ b/library/std/src/os/windows/ffi.rs
@@ -141,7 +141,7 @@ impl OsStrExt for OsStr {
 pub struct EncodeWide<'a> {
     inner: alloc::wtf8::EncodeWide<'a>,
 }
-#[stable(feature = "encode_wide_debug", since = "CURRENT_RUSTC_VERSION")]
+#[stable(feature = "encode_wide_debug", since = "1.91.0")]
 impl fmt::Debug for EncodeWide<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt::Debug::fmt(&self.inner, f)
diff --git a/library/std/src/panic.rs b/library/std/src/panic.rs
index 5e8d2f8e78e..1997785885d 100644
--- a/library/std/src/panic.rs
+++ b/library/std/src/panic.rs
@@ -122,7 +122,7 @@ impl<'a> PanicHookInfo<'a> {
     /// ```
     #[must_use]
     #[inline]
-    #[stable(feature = "panic_payload_as_str", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "panic_payload_as_str", since = "1.91.0")]
     pub fn payload_as_str(&self) -> Option<&str> {
         if let Some(s) = self.payload.downcast_ref::<&str>() {
             Some(s)
diff --git a/library/std/src/panicking.rs b/library/std/src/panicking.rs
index 8b7282c51d1..b7be869c4eb 100644
--- a/library/std/src/panicking.rs
+++ b/library/std/src/panicking.rs
@@ -331,7 +331,7 @@ fn default_hook(info: &PanicHookInfo<'_>) {
 
 #[cfg(not(test))]
 #[doc(hidden)]
-#[cfg(feature = "panic_immediate_abort")]
+#[cfg(panic = "immediate-abort")]
 #[unstable(feature = "update_panic_count", issue = "none")]
 pub mod panic_count {
     /// A reason for forcing an immediate abort on panic.
@@ -371,7 +371,7 @@ pub mod panic_count {
 
 #[cfg(not(test))]
 #[doc(hidden)]
-#[cfg(not(feature = "panic_immediate_abort"))]
+#[cfg(not(panic = "immediate-abort"))]
 #[unstable(feature = "update_panic_count", issue = "none")]
 pub mod panic_count {
     use crate::cell::Cell;
@@ -499,13 +499,13 @@ pub mod panic_count {
 pub use realstd::rt::panic_count;
 
 /// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
-#[cfg(feature = "panic_immediate_abort")]
+#[cfg(panic = "immediate-abort")]
 pub unsafe fn catch_unwind<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
     Ok(f())
 }
 
 /// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
-#[cfg(not(feature = "panic_immediate_abort"))]
+#[cfg(not(panic = "immediate-abort"))]
 pub unsafe fn catch_unwind<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
     union Data<F, R> {
         f: ManuallyDrop<F>,
@@ -720,14 +720,14 @@ pub fn panic_handler(info: &core::panic::PanicInfo<'_>) -> ! {
 #[unstable(feature = "libstd_sys_internals", reason = "used by the panic! macro", issue = "none")]
 #[cfg_attr(not(any(test, doctest)), lang = "begin_panic")]
 // lang item for CTFE panic support
-// never inline unless panic_immediate_abort to avoid code
+// never inline unless panic=immediate-abort to avoid code
 // bloat at the call sites as much as possible
-#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never), cold, optimize(size))]
-#[cfg_attr(feature = "panic_immediate_abort", inline)]
+#[cfg_attr(not(panic = "immediate-abort"), inline(never), cold, optimize(size))]
+#[cfg_attr(panic = "immediate-abort", inline)]
 #[track_caller]
 #[rustc_do_not_const_check] // hooked by const-eval
 pub const fn begin_panic<M: Any + Send>(msg: M) -> ! {
-    if cfg!(feature = "panic_immediate_abort") {
+    if cfg!(panic = "immediate-abort") {
         intrinsics::abort()
     }
 
@@ -861,7 +861,7 @@ fn panic_with_hook(
 
 /// This is the entry point for `resume_unwind`.
 /// It just forwards the payload to the panic runtime.
-#[cfg_attr(feature = "panic_immediate_abort", inline)]
+#[cfg_attr(panic = "immediate-abort", inline)]
 pub fn resume_unwind(payload: Box<dyn Any + Send>) -> ! {
     panic_count::increase(false);
 
@@ -890,16 +890,14 @@ pub fn resume_unwind(payload: Box<dyn Any + Send>) -> ! {
 /// on which to slap yer breakpoints.
 #[inline(never)]
 #[cfg_attr(not(test), rustc_std_internal_symbol)]
-#[cfg(not(feature = "panic_immediate_abort"))]
+#[cfg(not(panic = "immediate-abort"))]
 fn rust_panic(msg: &mut dyn PanicPayload) -> ! {
     let code = unsafe { __rust_start_panic(msg) };
     rtabort!("failed to initiate panic, error {code}")
 }
 
 #[cfg_attr(not(test), rustc_std_internal_symbol)]
-#[cfg(feature = "panic_immediate_abort")]
+#[cfg(panic = "immediate-abort")]
 fn rust_panic(_: &mut dyn PanicPayload) -> ! {
-    unsafe {
-        crate::intrinsics::abort();
-    }
+    crate::intrinsics::abort();
 }
diff --git a/library/std/src/path.rs b/library/std/src/path.rs
index 70ba502d684..6e3b1e6e47d 100644
--- a/library/std/src/path.rs
+++ b/library/std/src/path.rs
@@ -1191,7 +1191,7 @@ impl PathBuf {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     #[inline]
-    #[rustc_const_stable(feature = "const_pathbuf_osstring_new", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_pathbuf_osstring_new", since = "1.91.0")]
     pub const fn new() -> PathBuf {
         PathBuf { inner: OsString::new() }
     }
@@ -1412,6 +1412,99 @@ impl PathBuf {
         }
     }
 
+    /// Sets whether the path has a trailing [separator](MAIN_SEPARATOR).
+    ///
+    /// The value returned by [`has_trailing_sep`](Path::has_trailing_sep) will be equivalent to
+    /// the provided value if possible.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(path_trailing_sep)]
+    /// use std::path::PathBuf;
+    ///
+    /// let mut p = PathBuf::from("dir");
+    ///
+    /// assert!(!p.has_trailing_sep());
+    /// p.set_trailing_sep(false);
+    /// assert!(!p.has_trailing_sep());
+    /// p.set_trailing_sep(true);
+    /// assert!(p.has_trailing_sep());
+    /// p.set_trailing_sep(false);
+    /// assert!(!p.has_trailing_sep());
+    ///
+    /// p = PathBuf::from("/");
+    /// assert!(p.has_trailing_sep());
+    /// p.set_trailing_sep(false);
+    /// assert!(p.has_trailing_sep());
+    /// ```
+    #[unstable(feature = "path_trailing_sep", issue = "142503")]
+    pub fn set_trailing_sep(&mut self, trailing_sep: bool) {
+        if trailing_sep { self.push_trailing_sep() } else { self.pop_trailing_sep() }
+    }
+
+    /// Adds a trailing [separator](MAIN_SEPARATOR) to the path.
+    ///
+    /// This acts similarly to [`Path::with_trailing_sep`], but mutates the underlying `PathBuf`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(path_trailing_sep)]
+    /// use std::ffi::OsStr;
+    /// use std::path::PathBuf;
+    ///
+    /// let mut p = PathBuf::from("dir");
+    ///
+    /// assert!(!p.has_trailing_sep());
+    /// p.push_trailing_sep();
+    /// assert!(p.has_trailing_sep());
+    /// p.push_trailing_sep();
+    /// assert!(p.has_trailing_sep());
+    ///
+    /// p = PathBuf::from("dir/");
+    /// p.push_trailing_sep();
+    /// assert_eq!(p.as_os_str(), OsStr::new("dir/"));
+    /// ```
+    #[unstable(feature = "path_trailing_sep", issue = "142503")]
+    pub fn push_trailing_sep(&mut self) {
+        if !self.has_trailing_sep() {
+            self.push("");
+        }
+    }
+
+    /// Removes a trailing [separator](MAIN_SEPARATOR) from the path, if possible.
+    ///
+    /// This acts similarly to [`Path::trim_trailing_sep`], but mutates the underlying `PathBuf`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(path_trailing_sep)]
+    /// use std::ffi::OsStr;
+    /// use std::path::PathBuf;
+    ///
+    /// let mut p = PathBuf::from("dir//");
+    ///
+    /// assert!(p.has_trailing_sep());
+    /// assert_eq!(p.as_os_str(), OsStr::new("dir//"));
+    /// p.pop_trailing_sep();
+    /// assert!(!p.has_trailing_sep());
+    /// assert_eq!(p.as_os_str(), OsStr::new("dir"));
+    /// p.pop_trailing_sep();
+    /// assert!(!p.has_trailing_sep());
+    /// assert_eq!(p.as_os_str(), OsStr::new("dir"));
+    ///
+    /// p = PathBuf::from("/");
+    /// assert!(p.has_trailing_sep());
+    /// p.pop_trailing_sep();
+    /// assert!(p.has_trailing_sep());
+    /// ```
+    #[unstable(feature = "path_trailing_sep", issue = "142503")]
+    pub fn pop_trailing_sep(&mut self) {
+        self.inner.truncate(self.trim_trailing_sep().as_os_str().len());
+    }
+
     /// Updates [`self.file_name`] to `file_name`.
     ///
     /// If [`self.file_name`] was [`None`], this is equivalent to pushing
@@ -1594,7 +1687,7 @@ impl PathBuf {
     /// p.add_extension("");
     /// assert_eq!(Path::new("/feel/the.formatted.dark"), p.as_path());
     /// ```
-    #[stable(feature = "path_add_extension", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "path_add_extension", since = "1.91.0")]
     pub fn add_extension<S: AsRef<OsStr>>(&mut self, extension: S) -> bool {
         self._add_extension(extension.as_ref())
     }
@@ -1610,7 +1703,7 @@ impl PathBuf {
         let new = extension.as_encoded_bytes();
         if !new.is_empty() {
             // truncate until right after the file name
-            // this is necessary for trimming the trailing slash
+            // this is necessary for trimming the trailing separator
             let end_file_name = file_name[file_name.len()..].as_ptr().addr();
             let start = self.inner.as_encoded_bytes().as_ptr().addr();
             self.inner.truncate(end_file_name.wrapping_sub(start));
@@ -2103,35 +2196,35 @@ impl PartialEq for PathBuf {
     }
 }
 
-#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+#[stable(feature = "eq_str_for_path", since = "1.91.0")]
 impl cmp::PartialEq<str> for PathBuf {
     #[inline]
     fn eq(&self, other: &str) -> bool {
-        Path::eq(self, other)
+        self.as_path() == other
     }
 }
 
-#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+#[stable(feature = "eq_str_for_path", since = "1.91.0")]
 impl cmp::PartialEq<PathBuf> for str {
     #[inline]
     fn eq(&self, other: &PathBuf) -> bool {
-        other == self
+        self == other.as_path()
     }
 }
 
-#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+#[stable(feature = "eq_str_for_path", since = "1.91.0")]
 impl cmp::PartialEq<String> for PathBuf {
     #[inline]
     fn eq(&self, other: &String) -> bool {
-        **self == **other
+        self.as_path() == other.as_str()
     }
 }
 
-#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+#[stable(feature = "eq_str_for_path", since = "1.91.0")]
 impl cmp::PartialEq<PathBuf> for String {
     #[inline]
     fn eq(&self, other: &PathBuf) -> bool {
-        other == self
+        self.as_str() == other.as_path()
     }
 }
 
@@ -2724,7 +2817,7 @@ impl Path {
     ///
     /// [`Path::file_stem`]: Path::file_stem
     ///
-    #[stable(feature = "path_file_prefix", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "path_file_prefix", since = "1.91.0")]
     #[must_use]
     pub fn file_prefix(&self) -> Option<&OsStr> {
         self.file_name().map(split_file_at_dot).and_then(|(before, _after)| Some(before))
@@ -2755,6 +2848,94 @@ impl Path {
         self.file_name().map(rsplit_file_at_dot).and_then(|(before, after)| before.and(after))
     }
 
+    /// Checks whether the path ends in a trailing [separator](MAIN_SEPARATOR).
+    ///
+    /// This is generally done to ensure that a path is treated as a directory, not a file,
+    /// although it does not actually guarantee that such a path is a directory on the underlying
+    /// file system.
+    ///
+    /// Despite this behavior, two paths are still considered the same in Rust whether they have a
+    /// trailing separator or not.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(path_trailing_sep)]
+    /// use std::path::Path;
+    ///
+    /// assert!(Path::new("dir/").has_trailing_sep());
+    /// assert!(!Path::new("file.rs").has_trailing_sep());
+    /// ```
+    #[unstable(feature = "path_trailing_sep", issue = "142503")]
+    #[must_use]
+    #[inline]
+    pub fn has_trailing_sep(&self) -> bool {
+        self.as_os_str().as_encoded_bytes().last().copied().is_some_and(is_sep_byte)
+    }
+
+    /// Ensures that a path has a trailing [separator](MAIN_SEPARATOR),
+    /// allocating a [`PathBuf`] if necessary.
+    ///
+    /// The resulting path will return true for [`has_trailing_sep`](Self::has_trailing_sep).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(path_trailing_sep)]
+    /// use std::ffi::OsStr;
+    /// use std::path::Path;
+    ///
+    /// assert_eq!(Path::new("dir//").with_trailing_sep().as_os_str(), OsStr::new("dir//"));
+    /// assert_eq!(Path::new("dir/").with_trailing_sep().as_os_str(), OsStr::new("dir/"));
+    /// assert!(!Path::new("dir").has_trailing_sep());
+    /// assert!(Path::new("dir").with_trailing_sep().has_trailing_sep());
+    /// ```
+    #[unstable(feature = "path_trailing_sep", issue = "142503")]
+    #[must_use]
+    #[inline]
+    pub fn with_trailing_sep(&self) -> Cow<'_, Path> {
+        if self.has_trailing_sep() { Cow::Borrowed(self) } else { Cow::Owned(self.join("")) }
+    }
+
+    /// Trims a trailing [separator](MAIN_SEPARATOR) from a path, if possible.
+    ///
+    /// The resulting path will return false for [`has_trailing_sep`](Self::has_trailing_sep) for
+    /// most paths.
+    ///
+    /// Some paths, like `/`, cannot be trimmed in this way.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(path_trailing_sep)]
+    /// use std::ffi::OsStr;
+    /// use std::path::Path;
+    ///
+    /// assert_eq!(Path::new("dir//").trim_trailing_sep().as_os_str(), OsStr::new("dir"));
+    /// assert_eq!(Path::new("dir/").trim_trailing_sep().as_os_str(), OsStr::new("dir"));
+    /// assert_eq!(Path::new("dir").trim_trailing_sep().as_os_str(), OsStr::new("dir"));
+    /// assert_eq!(Path::new("/").trim_trailing_sep().as_os_str(), OsStr::new("/"));
+    /// assert_eq!(Path::new("//").trim_trailing_sep().as_os_str(), OsStr::new("//"));
+    /// ```
+    #[unstable(feature = "path_trailing_sep", issue = "142503")]
+    #[must_use]
+    #[inline]
+    pub fn trim_trailing_sep(&self) -> &Path {
+        if self.has_trailing_sep() && (!self.has_root() || self.parent().is_some()) {
+            let mut bytes = self.inner.as_encoded_bytes();
+            while let Some((last, init)) = bytes.split_last()
+                && is_sep_byte(*last)
+            {
+                bytes = init;
+            }
+
+            // SAFETY: Trimming trailing ASCII bytes will retain the validity of the string.
+            Path::new(unsafe { OsStr::from_encoded_bytes_unchecked(bytes) })
+        } else {
+            self
+        }
+    }
+
     /// Creates an owned [`PathBuf`] with `path` adjoined to `self`.
     ///
     /// If `path` is absolute, it replaces the current path.
@@ -2888,7 +3069,7 @@ impl Path {
     /// assert_eq!(path.with_added_extension("xz"), PathBuf::from("foo.tar.gz.xz"));
     /// assert_eq!(path.with_added_extension("").with_added_extension("txt"), PathBuf::from("foo.tar.gz.txt"));
     /// ```
-    #[stable(feature = "path_add_extension", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "path_add_extension", since = "1.91.0")]
     pub fn with_added_extension<S: AsRef<OsStr>>(&self, extension: S) -> PathBuf {
         let mut new_path = self.to_path_buf();
         new_path.add_extension(extension);
@@ -2907,7 +3088,7 @@ impl Path {
     ///   `a/b` all have `a` and `b` as components, but `./a/b` starts with
     ///   an additional [`CurDir`] component.
     ///
-    /// * A trailing slash is normalized away, `/a/b` and `/a/b/` are equivalent.
+    /// * Trailing separators are normalized away, so `/a/b` and `/a/b/` are equivalent.
     ///
     /// Note that no other normalization takes place; in particular, `a/c`
     /// and `a/b/../c` are distinct, to account for the possibility that `b`
@@ -3405,7 +3586,7 @@ impl PartialEq for Path {
     }
 }
 
-#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+#[stable(feature = "eq_str_for_path", since = "1.91.0")]
 impl cmp::PartialEq<str> for Path {
     #[inline]
     fn eq(&self, other: &str) -> bool {
@@ -3414,7 +3595,7 @@ impl cmp::PartialEq<str> for Path {
     }
 }
 
-#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+#[stable(feature = "eq_str_for_path", since = "1.91.0")]
 impl cmp::PartialEq<Path> for str {
     #[inline]
     fn eq(&self, other: &Path) -> bool {
@@ -3422,19 +3603,19 @@ impl cmp::PartialEq<Path> for str {
     }
 }
 
-#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+#[stable(feature = "eq_str_for_path", since = "1.91.0")]
 impl cmp::PartialEq<String> for Path {
     #[inline]
     fn eq(&self, other: &String) -> bool {
-        self == &*other
+        self == other.as_str()
     }
 }
 
-#[stable(feature = "eq_str_for_path", since = "CURRENT_RUSTC_VERSION")]
+#[stable(feature = "eq_str_for_path", since = "1.91.0")]
 impl cmp::PartialEq<Path> for String {
     #[inline]
     fn eq(&self, other: &Path) -> bool {
-        other == self
+        self.as_str() == other
     }
 }
 
@@ -3718,7 +3899,7 @@ impl Error for NormalizeError {}
 ///
 /// On POSIX platforms, the path is resolved using [POSIX semantics][posix-semantics],
 /// except that it stops short of resolving symlinks. This means it will keep `..`
-/// components and trailing slashes.
+/// components and trailing separators.
 ///
 /// On Windows, for verbatim paths, this will simply return the path as given. For other
 /// paths, this is currently equivalent to calling
diff --git a/library/std/src/process.rs b/library/std/src/process.rs
index 48265de90c4..5c0ac526a36 100644
--- a/library/std/src/process.rs
+++ b/library/std/src/process.rs
@@ -268,8 +268,8 @@ impl AsInner<imp::Process> for Child {
     }
 }
 
-impl FromInner<(imp::Process, imp::StdioPipes)> for Child {
-    fn from_inner((handle, io): (imp::Process, imp::StdioPipes)) -> Child {
+impl FromInner<(imp::Process, StdioPipes)> for Child {
+    fn from_inner((handle, io): (imp::Process, StdioPipes)) -> Child {
         Child {
             handle,
             stdin: io.stdin.map(ChildStdin::from_inner),
@@ -296,6 +296,15 @@ impl fmt::Debug for Child {
     }
 }
 
+/// The pipes connected to a spawned process.
+///
+/// Used to pass pipe handles between this module and [`imp`].
+pub(crate) struct StdioPipes {
+    pub stdin: Option<AnonPipe>,
+    pub stdout: Option<AnonPipe>,
+    pub stderr: Option<AnonPipe>,
+}
+
 /// A handle to a child process's standard input (stdin).
 ///
 /// This struct is used in the [`stdin`] field on [`Child`].
@@ -532,6 +541,7 @@ impl fmt::Debug for ChildStderr {
 /// to be changed (for example, by adding arguments) prior to spawning:
 ///
 /// ```
+/// # if cfg!(not(all(target_vendor = "apple", not(target_os = "macos")))) {
 /// use std::process::Command;
 ///
 /// let output = if cfg!(target_os = "windows") {
@@ -548,6 +558,7 @@ impl fmt::Debug for ChildStderr {
 /// };
 ///
 /// let hello = output.stdout;
+/// # }
 /// ```
 ///
 /// `Command` can be reused to spawn multiple processes. The builder methods
@@ -1348,7 +1359,7 @@ impl Output {
     ///
     /// ```
     /// #![feature(exit_status_error)]
-    /// # #[cfg(all(unix, not(target_os = "android")))] {
+    /// # #[cfg(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos")))))] {
     /// use std::process::Command;
     /// assert!(Command::new("false").output().unwrap().exit_ok().is_err());
     /// # }
@@ -1695,7 +1706,7 @@ impl From<io::Stdout> for Stdio {
     /// # Ok(())
     /// # }
     /// #
-    /// # if cfg!(all(unix, not(target_os = "android"))) {
+    /// # if cfg!(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos"))))) {
     /// #     test().unwrap();
     /// # }
     /// ```
@@ -1724,7 +1735,7 @@ impl From<io::Stderr> for Stdio {
     /// # Ok(())
     /// # }
     /// #
-    /// # if cfg!(all(unix, not(target_os = "android"))) {
+    /// # if cfg!(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos"))))) {
     /// #     test().unwrap();
     /// # }
     /// ```
@@ -1800,7 +1811,7 @@ impl ExitStatus {
     ///
     /// ```
     /// #![feature(exit_status_error)]
-    /// # if cfg!(unix) {
+    /// # if cfg!(all(unix, not(all(target_vendor = "apple", not(target_os = "macos"))))) {
     /// use std::process::Command;
     ///
     /// let status = Command::new("ls")
@@ -1907,7 +1918,7 @@ impl crate::sealed::Sealed for ExitStatusError {}
 ///
 /// ```
 /// #![feature(exit_status_error)]
-/// # if cfg!(all(unix, not(target_os = "android"))) {
+/// # if cfg!(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos"))))) {
 /// use std::process::{Command, ExitStatusError};
 ///
 /// fn run(cmd: &str) -> Result<(), ExitStatusError> {
@@ -1950,7 +1961,7 @@ impl ExitStatusError {
     ///
     /// ```
     /// #![feature(exit_status_error)]
-    /// # #[cfg(all(unix, not(target_os = "android")))] {
+    /// # #[cfg(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos")))))] {
     /// use std::process::Command;
     ///
     /// let bad = Command::new("false").status().unwrap().exit_ok().unwrap_err();
@@ -1975,7 +1986,7 @@ impl ExitStatusError {
     /// ```
     /// #![feature(exit_status_error)]
     ///
-    /// # if cfg!(all(unix, not(target_os = "android"))) {
+    /// # if cfg!(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos"))))) {
     /// use std::num::NonZero;
     /// use std::process::Command;
     ///
diff --git a/library/std/src/process/tests.rs b/library/std/src/process/tests.rs
index 5879914ca20..12c5130defe 100644
--- a/library/std/src/process/tests.rs
+++ b/library/std/src/process/tests.rs
@@ -5,7 +5,15 @@ use crate::mem::MaybeUninit;
 use crate::str;
 
 fn known_command() -> Command {
-    if cfg!(windows) { Command::new("help") } else { Command::new("echo") }
+    if cfg!(windows) {
+        Command::new("help")
+    } else if cfg!(all(target_vendor = "apple", not(target_os = "macos"))) {
+        // iOS/tvOS/watchOS/visionOS have a very limited set of commandline
+        // binaries available.
+        Command::new("log")
+    } else {
+        Command::new("echo")
+    }
 }
 
 #[cfg(target_os = "android")]
@@ -19,7 +27,10 @@ fn shell_cmd() -> Command {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn smoke() {
     let p = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "exit 0"]).spawn()
@@ -41,7 +52,10 @@ fn smoke_failure() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn exit_reported_right() {
     let p = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "exit 1"]).spawn()
@@ -56,7 +70,10 @@ fn exit_reported_right() {
 
 #[test]
 #[cfg(unix)]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn signal_reported_right() {
     use crate::os::unix::process::ExitStatusExt;
 
@@ -80,7 +97,10 @@ pub fn run_output(mut cmd: Command) -> String {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn stdout_works() {
     if cfg!(target_os = "windows") {
         let mut cmd = Command::new("cmd");
@@ -94,7 +114,11 @@ fn stdout_works() {
 }
 
 #[test]
-#[cfg_attr(any(windows, target_os = "vxworks"), ignore)]
+#[cfg_attr(windows, ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn set_current_dir_works() {
     // On many Unix platforms this will use the posix_spawn path.
     let mut cmd = shell_cmd();
@@ -116,7 +140,11 @@ fn set_current_dir_works() {
 }
 
 #[test]
-#[cfg_attr(any(windows, target_os = "vxworks"), ignore)]
+#[cfg_attr(windows, ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn stdin_works() {
     let mut p = shell_cmd()
         .arg("-c")
@@ -134,7 +162,10 @@ fn stdin_works() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn child_stdout_read_buf() {
     let mut cmd = if cfg!(target_os = "windows") {
         let mut cmd = Command::new("cmd");
@@ -165,7 +196,10 @@ fn child_stdout_read_buf() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_process_status() {
     let mut status = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "exit 1"]).status().unwrap()
@@ -191,7 +225,10 @@ fn test_process_output_fail_to_start() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_process_output_output() {
     let Output { status, stdout, stderr } = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "echo hello"]).output().unwrap()
@@ -206,7 +243,10 @@ fn test_process_output_output() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_process_output_error() {
     let Output { status, stdout, stderr } = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "mkdir ."]).output().unwrap()
@@ -221,7 +261,10 @@ fn test_process_output_error() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_finish_once() {
     let mut prog = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "exit 1"]).spawn().unwrap()
@@ -232,7 +275,10 @@ fn test_finish_once() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_finish_twice() {
     let mut prog = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "exit 1"]).spawn().unwrap()
@@ -244,7 +290,10 @@ fn test_finish_twice() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_wait_with_output_once() {
     let prog = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "echo hello"]).stdout(Stdio::piped()).spawn().unwrap()
@@ -279,7 +328,10 @@ pub fn env_cmd() -> Command {
 }
 
 #[test]
-#[cfg_attr(target_os = "vxworks", ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_override_env() {
     use crate::env;
 
@@ -302,7 +354,10 @@ fn test_override_env() {
 }
 
 #[test]
-#[cfg_attr(target_os = "vxworks", ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_add_to_env() {
     let result = env_cmd().env("RUN_TEST_NEW_ENV", "123").output().unwrap();
     let output = String::from_utf8_lossy(&result.stdout).to_string();
@@ -314,7 +369,10 @@ fn test_add_to_env() {
 }
 
 #[test]
-#[cfg_attr(target_os = "vxworks", ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_capture_env_at_spawn() {
     use crate::env;
 
@@ -378,7 +436,10 @@ fn test_interior_nul_in_current_dir_is_error() {
 
 // Regression tests for #30862.
 #[test]
-#[cfg_attr(target_os = "vxworks", ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no `env` cmd available"
+)]
 fn test_interior_nul_in_env_key_is_error() {
     match env_cmd().env("has-some-\0\0s-inside", "value").spawn() {
         Err(e) => assert_eq!(e.kind(), ErrorKind::InvalidInput),
@@ -387,7 +448,10 @@ fn test_interior_nul_in_env_key_is_error() {
 }
 
 #[test]
-#[cfg_attr(target_os = "vxworks", ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no `env` cmd available"
+)]
 fn test_interior_nul_in_env_value_is_error() {
     match env_cmd().env("key", "has-some-\0\0s-inside").spawn() {
         Err(e) => assert_eq!(e.kind(), ErrorKind::InvalidInput),
diff --git a/library/std/src/rt.rs b/library/std/src/rt.rs
index b3f3b301e3d..2717b7b469c 100644
--- a/library/std/src/rt.rs
+++ b/library/std/src/rt.rs
@@ -39,11 +39,11 @@ fn __rust_abort() {
 // - nothing (so this macro is a no-op)
 macro_rules! rtprintpanic {
     ($($t:tt)*) => {
-        #[cfg(not(feature = "panic_immediate_abort"))]
+        #[cfg(not(panic = "immediate-abort"))]
         if let Some(mut out) = crate::sys::stdio::panic_output() {
             let _ = crate::io::Write::write_fmt(&mut out, format_args!($($t)*));
         }
-        #[cfg(feature = "panic_immediate_abort")]
+        #[cfg(panic = "immediate-abort")]
         {
             let _ = format_args!($($t)*);
         }
@@ -161,7 +161,7 @@ fn lang_start_internal(
     // mechanism itself.
     //
     // There are a couple of instances where unwinding can begin. First is inside of the
-    // `rt::init`, `rt::cleanup` and similar functions controlled by bstd. In those instances a
+    // `rt::init`, `rt::cleanup` and similar functions controlled by std. In those instances a
     // panic is a std implementation bug. A quite likely one too, as there isn't any way to
     // prevent std from accidentally introducing a panic to these functions. Another is from
     // user code from `main` or, more nefariously, as described in e.g. issue #86030.
diff --git a/library/std/src/sync/nonpoison/condvar.rs b/library/std/src/sync/nonpoison/condvar.rs
index 49afdd87818..994fc6816a0 100644
--- a/library/std/src/sync/nonpoison/condvar.rs
+++ b/library/std/src/sync/nonpoison/condvar.rs
@@ -198,11 +198,10 @@ impl Condvar {
     /// the system time. This function is susceptible to spurious wakeups.
     /// Condition variables normally have a boolean predicate associated with
     /// them, and the predicate must always be checked each time this function
-    /// returns to protect against spurious wakeups. Additionally, it is
-    /// typically desirable for the timeout to not exceed some duration in
-    /// spite of spurious wakes, thus the sleep-duration is decremented by the
-    /// amount slept. Alternatively, use the `wait_timeout_while` method
-    /// to wait with a timeout while a predicate is true.
+    /// returns to protect against spurious wakeups.  Furthermore, since the timeout
+    /// is given relative to the moment this function is called, it needs to be adjusted
+    /// when this function is called in a loop. The [`wait_timeout_while`] method
+    /// lets you wait with a timeout while a predicate is true, taking care of all these concerns.
     ///
     /// The returned [`WaitTimeoutResult`] value indicates if the timeout is
     /// known to have elapsed.
diff --git a/library/std/src/sync/nonpoison/mutex.rs b/library/std/src/sync/nonpoison/mutex.rs
index 07430ce3a13..eeecf5d7107 100644
--- a/library/std/src/sync/nonpoison/mutex.rs
+++ b/library/std/src/sync/nonpoison/mutex.rs
@@ -373,7 +373,7 @@ impl<T: ?Sized> Mutex<T> {
     /// or written through after the mutex is dropped.
     #[unstable(feature = "mutex_data_ptr", issue = "140368")]
     // #[unstable(feature = "nonpoison_mutex", issue = "134645")]
-    pub fn data_ptr(&self) -> *mut T {
+    pub const fn data_ptr(&self) -> *mut T {
         self.data.get()
     }
 }
diff --git a/library/std/src/sync/nonpoison/rwlock.rs b/library/std/src/sync/nonpoison/rwlock.rs
index eb0aef99cc1..b2f26edc083 100644
--- a/library/std/src/sync/nonpoison/rwlock.rs
+++ b/library/std/src/sync/nonpoison/rwlock.rs
@@ -495,7 +495,7 @@ impl<T: ?Sized> RwLock<T> {
     /// or written through after the lock is dropped.
     #[unstable(feature = "rwlock_data_ptr", issue = "140368")]
     // #[unstable(feature = "nonpoison_rwlock", issue = "134645")]
-    pub fn data_ptr(&self) -> *mut T {
+    pub const fn data_ptr(&self) -> *mut T {
         self.data.get()
     }
 }
diff --git a/library/std/src/sync/poison/condvar.rs b/library/std/src/sync/poison/condvar.rs
index 5dc2b510f3a..de625a6cc5f 100644
--- a/library/std/src/sync/poison/condvar.rs
+++ b/library/std/src/sync/poison/condvar.rs
@@ -269,11 +269,10 @@ impl Condvar {
     /// the system time. This function is susceptible to spurious wakeups.
     /// Condition variables normally have a boolean predicate associated with
     /// them, and the predicate must always be checked each time this function
-    /// returns to protect against spurious wakeups. Additionally, it is
-    /// typically desirable for the timeout to not exceed some duration in
-    /// spite of spurious wakes, thus the sleep-duration is decremented by the
-    /// amount slept. Alternatively, use the `wait_timeout_while` method
-    /// to wait with a timeout while a predicate is true.
+    /// returns to protect against spurious wakeups. Furthermore, since the timeout
+    /// is given relative to the moment this function is called, it needs to be adjusted
+    /// when this function is called in a loop. The [`wait_timeout_while`] method
+    /// lets you wait with a timeout while a predicate is true, taking care of all these concerns.
     ///
     /// The returned [`WaitTimeoutResult`] value indicates if the timeout is
     /// known to have elapsed.
diff --git a/library/std/src/sync/poison/mutex.rs b/library/std/src/sync/poison/mutex.rs
index 7e9d920d92f..6fdb4f6799e 100644
--- a/library/std/src/sync/poison/mutex.rs
+++ b/library/std/src/sync/poison/mutex.rs
@@ -668,7 +668,7 @@ impl<T: ?Sized> Mutex<T> {
     /// are properly synchronized to avoid data races, and that it is not read
     /// or written through after the mutex is dropped.
     #[unstable(feature = "mutex_data_ptr", issue = "140368")]
-    pub fn data_ptr(&self) -> *mut T {
+    pub const fn data_ptr(&self) -> *mut T {
         self.data.get()
     }
 }
diff --git a/library/std/src/sync/poison/rwlock.rs b/library/std/src/sync/poison/rwlock.rs
index 0a463f3f9c7..e3a72c73bf4 100644
--- a/library/std/src/sync/poison/rwlock.rs
+++ b/library/std/src/sync/poison/rwlock.rs
@@ -667,7 +667,7 @@ impl<T: ?Sized> RwLock<T> {
     /// are properly synchronized to avoid data races, and that it is not read
     /// or written through after the lock is dropped.
     #[unstable(feature = "rwlock_data_ptr", issue = "140368")]
-    pub fn data_ptr(&self) -> *mut T {
+    pub const fn data_ptr(&self) -> *mut T {
         self.data.get()
     }
 }
diff --git a/library/std/src/sync/reentrant_lock.rs b/library/std/src/sync/reentrant_lock.rs
index 4140718560c..f560b616dd9 100644
--- a/library/std/src/sync/reentrant_lock.rs
+++ b/library/std/src/sync/reentrant_lock.rs
@@ -355,7 +355,7 @@ impl<T: ?Sized> ReentrantLock<T> {
     /// properly synchronized to avoid data races, and that it is not read
     /// through after the lock is dropped.
     #[unstable(feature = "reentrant_lock_data_ptr", issue = "140368")]
-    pub fn data_ptr(&self) -> *const T {
+    pub const fn data_ptr(&self) -> *const T {
         &raw const self.data
     }
 
diff --git a/library/std/src/sys/alloc/mod.rs b/library/std/src/sys/alloc/mod.rs
index 6d4b09494a3..2045b2fecc6 100644
--- a/library/std/src/sys/alloc/mod.rs
+++ b/library/std/src/sys/alloc/mod.rs
@@ -92,6 +92,9 @@ cfg_select! {
     target_os = "uefi" => {
         mod uefi;
     }
+    target_os = "vexos" => {
+        mod vexos;
+    }
     target_family = "wasm" => {
         mod wasm;
     }
diff --git a/library/std/src/sys/alloc/vexos.rs b/library/std/src/sys/alloc/vexos.rs
new file mode 100644
index 00000000000..c1fb6896a89
--- /dev/null
+++ b/library/std/src/sys/alloc/vexos.rs
@@ -0,0 +1,96 @@
+// FIXME(static_mut_refs): Do not allow `static_mut_refs` lint
+#![allow(static_mut_refs)]
+
+use crate::alloc::{GlobalAlloc, Layout, System};
+use crate::ptr;
+use crate::sync::atomic::{AtomicBool, Ordering};
+
+// Symbols for heap section boundaries defined in the target's linkerscript
+unsafe extern "C" {
+    static mut __heap_start: u8;
+    static mut __heap_end: u8;
+}
+
+static mut DLMALLOC: dlmalloc::Dlmalloc<Vexos> = dlmalloc::Dlmalloc::new_with_allocator(Vexos);
+
+struct Vexos;
+
+unsafe impl dlmalloc::Allocator for Vexos {
+    /// Allocs system resources
+    fn alloc(&self, _size: usize) -> (*mut u8, usize, u32) {
+        static INIT: AtomicBool = AtomicBool::new(false);
+
+        if !INIT.swap(true, Ordering::Relaxed) {
+            // This target has no growable heap, as user memory has a fixed
+            // size/location and VEXos does not manage allocation for us.
+            unsafe {
+                (
+                    (&raw mut __heap_start).cast::<u8>(),
+                    (&raw const __heap_end).offset_from_unsigned(&raw const __heap_start),
+                    0,
+                )
+            }
+        } else {
+            (ptr::null_mut(), 0, 0)
+        }
+    }
+
+    fn remap(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize, _can_move: bool) -> *mut u8 {
+        ptr::null_mut()
+    }
+
+    fn free_part(&self, _ptr: *mut u8, _oldsize: usize, _newsize: usize) -> bool {
+        false
+    }
+
+    fn free(&self, _ptr: *mut u8, _size: usize) -> bool {
+        return false;
+    }
+
+    fn can_release_part(&self, _flags: u32) -> bool {
+        false
+    }
+
+    fn allocates_zeros(&self) -> bool {
+        false
+    }
+
+    fn page_size(&self) -> usize {
+        0x1000
+    }
+}
+
+#[stable(feature = "alloc_system_type", since = "1.28.0")]
+unsafe impl GlobalAlloc for System {
+    #[inline]
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which
+        // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used.
+        // Calling malloc() is safe because preconditions on this function match the trait method preconditions.
+        unsafe { DLMALLOC.malloc(layout.size(), layout.align()) }
+    }
+
+    #[inline]
+    unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+        // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which
+        // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used.
+        // Calling calloc() is safe because preconditions on this function match the trait method preconditions.
+        unsafe { DLMALLOC.calloc(layout.size(), layout.align()) }
+    }
+
+    #[inline]
+    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which
+        // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used.
+        // Calling free() is safe because preconditions on this function match the trait method preconditions.
+        unsafe { DLMALLOC.free(ptr, layout.size(), layout.align()) }
+    }
+
+    #[inline]
+    unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+        // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which
+        // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used.
+        // Calling realloc() is safe because preconditions on this function match the trait method preconditions.
+        unsafe { DLMALLOC.realloc(ptr, layout.size(), layout.align(), new_size) }
+    }
+}
diff --git a/library/std/src/sys/args/zkvm.rs b/library/std/src/sys/args/zkvm.rs
index 194ba7159d4..d26bf1eaff9 100644
--- a/library/std/src/sys/args/zkvm.rs
+++ b/library/std/src/sys/args/zkvm.rs
@@ -1,25 +1,20 @@
-use crate::ffi::OsString;
-use crate::fmt;
-use crate::sys::os_str;
+use crate::ffi::{OsStr, OsString};
+use crate::num::NonZero;
+use crate::sync::OnceLock;
 use crate::sys::pal::{WORD_SIZE, abi};
-use crate::sys_common::FromInner;
-
-pub struct Args {
-    i_forward: usize,
-    i_back: usize,
-    count: usize,
-}
+use crate::{fmt, ptr, slice};
 
 pub fn args() -> Args {
-    let count = unsafe { abi::sys_argc() };
-    Args { i_forward: 0, i_back: 0, count }
+    Args { iter: ARGS.get_or_init(|| get_args()).iter() }
 }
 
-impl Args {
-    /// Use sys_argv to get the arg at the requested index. Does not check that i is less than argc
-    /// and will not return if the index is out of bounds.
-    fn argv(i: usize) -> OsString {
-        let arg_len = unsafe { abi::sys_argv(crate::ptr::null_mut(), 0, i) };
+fn get_args() -> Vec<&'static OsStr> {
+    let argc = unsafe { abi::sys_argc() };
+    let mut args = Vec::with_capacity(argc);
+
+    for i in 0..argc {
+        // Get the size of the argument then the data.
+        let arg_len = unsafe { abi::sys_argv(ptr::null_mut(), 0, i) };
 
         let arg_len_words = (arg_len + WORD_SIZE - 1) / WORD_SIZE;
         let words = unsafe { abi::sys_alloc_words(arg_len_words) };
@@ -27,20 +22,24 @@ impl Args {
         let arg_len2 = unsafe { abi::sys_argv(words, arg_len_words, i) };
         debug_assert_eq!(arg_len, arg_len2);
 
-        // Convert to OsString.
-        //
-        // FIXME: We can probably get rid of the extra copy here if we
-        // reimplement "os_str" instead of just using the generic unix
-        // "os_str".
-        let arg_bytes: &[u8] =
-            unsafe { crate::slice::from_raw_parts(words.cast() as *const u8, arg_len) };
-        OsString::from_inner(os_str::Buf { inner: arg_bytes.to_vec() })
+        let arg_bytes = unsafe { slice::from_raw_parts(words.cast(), arg_len) };
+        args.push(unsafe { OsStr::from_encoded_bytes_unchecked(arg_bytes) });
     }
+    args
 }
 
+static ARGS: OnceLock<Vec<&'static OsStr>> = OnceLock::new();
+
+pub struct Args {
+    iter: slice::Iter<'static, &'static OsStr>,
+}
+
+impl !Send for Args {}
+impl !Sync for Args {}
+
 impl fmt::Debug for Args {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_list().finish()
+        self.iter.as_slice().fmt(f)
     }
 }
 
@@ -48,34 +47,48 @@ impl Iterator for Args {
     type Item = OsString;
 
     fn next(&mut self) -> Option<OsString> {
-        if self.i_forward >= self.count - self.i_back {
-            None
-        } else {
-            let arg = Self::argv(self.i_forward);
-            self.i_forward += 1;
-            Some(arg)
-        }
+        self.iter.next().map(|arg| arg.to_os_string())
     }
 
+    #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        (self.count, Some(self.count))
+        self.iter.size_hint()
     }
-}
 
-impl ExactSizeIterator for Args {
-    fn len(&self) -> usize {
-        self.count
+    #[inline]
+    fn count(self) -> usize {
+        self.iter.len()
+    }
+
+    fn last(self) -> Option<OsString> {
+        self.iter.last().map(|arg| arg.to_os_string())
+    }
+
+    #[inline]
+    fn advance_by(&mut self, n: usize) -> Result<(), NonZero<usize>> {
+        self.iter.advance_by(n)
     }
 }
 
 impl DoubleEndedIterator for Args {
     fn next_back(&mut self) -> Option<OsString> {
-        if self.i_back >= self.count - self.i_forward {
-            None
-        } else {
-            let arg = Self::argv(self.count - 1 - self.i_back);
-            self.i_back += 1;
-            Some(arg)
-        }
+        self.iter.next_back().map(|arg| arg.to_os_string())
+    }
+
+    #[inline]
+    fn advance_back_by(&mut self, n: usize) -> Result<(), NonZero<usize>> {
+        self.iter.advance_back_by(n)
+    }
+}
+
+impl ExactSizeIterator for Args {
+    #[inline]
+    fn len(&self) -> usize {
+        self.iter.len()
+    }
+
+    #[inline]
+    fn is_empty(&self) -> bool {
+        self.iter.is_empty()
     }
 }
diff --git a/library/std/src/sys/env_consts.rs b/library/std/src/sys/env_consts.rs
index 9683fd47cf9..573f540483b 100644
--- a/library/std/src/sys/env_consts.rs
+++ b/library/std/src/sys/env_consts.rs
@@ -2,7 +2,7 @@
 
 // Replaces the #[else] gate with #[cfg(not(any(…)))] of all the other gates.
 // This ensures that they must be mutually exclusive and do not have precedence
-// like cfg_if!.
+// like cfg_select!.
 macro cfg_unordered(
     $(#[cfg($cfg:meta)] $os:item)*
     #[else] $fallback:item
@@ -323,6 +323,17 @@ pub mod os {
     pub const EXE_EXTENSION: &str = "efi";
 }
 
+#[cfg(target_os = "vexos")]
+pub mod os {
+    pub const FAMILY: &str = "";
+    pub const OS: &str = "vexos";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = "";
+    pub const DLL_EXTENSION: &str = "";
+    pub const EXE_SUFFIX: &str = ".bin";
+    pub const EXE_EXTENSION: &str = "bin";
+}
+
 #[cfg(target_os = "visionos")]
 pub mod os {
     pub const FAMILY: &str = "unix";
diff --git a/library/std/src/sys/fs/mod.rs b/library/std/src/sys/fs/mod.rs
index 0276bf6e64c..64f5a6b36d3 100644
--- a/library/std/src/sys/fs/mod.rs
+++ b/library/std/src/sys/fs/mod.rs
@@ -35,6 +35,10 @@ cfg_select! {
         mod uefi;
         use uefi as imp;
     }
+    target_os = "vexos" => {
+        mod vexos;
+        use vexos as imp;
+    }
     target_os = "wasi" => {
         mod wasi;
         use wasi as imp;
diff --git a/library/std/src/sys/fs/unix.rs b/library/std/src/sys/fs/unix.rs
index dfd6ce56a76..33a1e7ff5e4 100644
--- a/library/std/src/sys/fs/unix.rs
+++ b/library/std/src/sys/fs/unix.rs
@@ -21,29 +21,31 @@ use libc::fstatat as fstatat64;
 #[cfg(any(all(target_os = "linux", not(target_env = "musl")), target_os = "hurd"))]
 use libc::fstatat64;
 #[cfg(any(
+    target_os = "aix",
     target_os = "android",
-    target_os = "solaris",
+    target_os = "freebsd",
     target_os = "fuchsia",
-    target_os = "redox",
     target_os = "illumos",
-    target_os = "aix",
     target_os = "nto",
+    target_os = "redox",
+    target_os = "solaris",
     target_os = "vita",
     all(target_os = "linux", target_env = "musl"),
 ))]
 use libc::readdir as readdir64;
 #[cfg(not(any(
+    target_os = "aix",
     target_os = "android",
-    target_os = "linux",
-    target_os = "solaris",
+    target_os = "freebsd",
+    target_os = "fuchsia",
+    target_os = "hurd",
     target_os = "illumos",
     target_os = "l4re",
-    target_os = "fuchsia",
-    target_os = "redox",
-    target_os = "aix",
+    target_os = "linux",
     target_os = "nto",
+    target_os = "redox",
+    target_os = "solaris",
     target_os = "vita",
-    target_os = "hurd",
 )))]
 use libc::readdir_r as readdir64_r;
 #[cfg(any(all(target_os = "linux", not(target_env = "musl")), target_os = "hurd"))]
@@ -271,16 +273,17 @@ unsafe impl Send for Dir {}
 unsafe impl Sync for Dir {}
 
 #[cfg(any(
+    target_os = "aix",
     target_os = "android",
-    target_os = "linux",
-    target_os = "solaris",
-    target_os = "illumos",
+    target_os = "freebsd",
     target_os = "fuchsia",
-    target_os = "redox",
-    target_os = "aix",
+    target_os = "hurd",
+    target_os = "illumos",
+    target_os = "linux",
     target_os = "nto",
+    target_os = "redox",
+    target_os = "solaris",
     target_os = "vita",
-    target_os = "hurd",
 ))]
 pub struct DirEntry {
     dir: Arc<InnerReadDir>,
@@ -295,16 +298,17 @@ pub struct DirEntry {
 // we're not using the immediate `d_name` on these targets. Keeping this as an
 // `entry` field in `DirEntry` helps reduce the `cfg` boilerplate elsewhere.
 #[cfg(any(
+    target_os = "aix",
     target_os = "android",
-    target_os = "linux",
-    target_os = "solaris",
-    target_os = "illumos",
+    target_os = "freebsd",
     target_os = "fuchsia",
-    target_os = "redox",
-    target_os = "aix",
+    target_os = "hurd",
+    target_os = "illumos",
+    target_os = "linux",
     target_os = "nto",
+    target_os = "redox",
+    target_os = "solaris",
     target_os = "vita",
-    target_os = "hurd",
 ))]
 struct dirent64_min {
     d_ino: u64,
@@ -319,16 +323,17 @@ struct dirent64_min {
 }
 
 #[cfg(not(any(
+    target_os = "aix",
     target_os = "android",
-    target_os = "linux",
-    target_os = "solaris",
-    target_os = "illumos",
+    target_os = "freebsd",
     target_os = "fuchsia",
-    target_os = "redox",
-    target_os = "aix",
+    target_os = "hurd",
+    target_os = "illumos",
+    target_os = "linux",
     target_os = "nto",
+    target_os = "redox",
+    target_os = "solaris",
     target_os = "vita",
-    target_os = "hurd",
 )))]
 pub struct DirEntry {
     dir: Arc<InnerReadDir>,
@@ -698,16 +703,17 @@ impl Iterator for ReadDir {
     type Item = io::Result<DirEntry>;
 
     #[cfg(any(
+        target_os = "aix",
         target_os = "android",
-        target_os = "linux",
-        target_os = "solaris",
+        target_os = "freebsd",
         target_os = "fuchsia",
-        target_os = "redox",
+        target_os = "hurd",
         target_os = "illumos",
-        target_os = "aix",
+        target_os = "linux",
         target_os = "nto",
+        target_os = "redox",
+        target_os = "solaris",
         target_os = "vita",
-        target_os = "hurd",
     ))]
     fn next(&mut self) -> Option<io::Result<DirEntry>> {
         use crate::sys::os::{errno, set_errno};
@@ -768,6 +774,9 @@ impl Iterator for ReadDir {
                 // only access those bytes.
                 #[cfg(not(target_os = "vita"))]
                 let entry = dirent64_min {
+                    #[cfg(target_os = "freebsd")]
+                    d_ino: (*entry_ptr).d_fileno,
+                    #[cfg(not(target_os = "freebsd"))]
                     d_ino: (*entry_ptr).d_ino as u64,
                     #[cfg(not(any(
                         target_os = "solaris",
@@ -791,16 +800,17 @@ impl Iterator for ReadDir {
     }
 
     #[cfg(not(any(
+        target_os = "aix",
         target_os = "android",
-        target_os = "linux",
-        target_os = "solaris",
+        target_os = "freebsd",
         target_os = "fuchsia",
-        target_os = "redox",
+        target_os = "hurd",
         target_os = "illumos",
-        target_os = "aix",
+        target_os = "linux",
         target_os = "nto",
+        target_os = "redox",
+        target_os = "solaris",
         target_os = "vita",
-        target_os = "hurd",
     )))]
     fn next(&mut self) -> Option<io::Result<DirEntry>> {
         if self.end_of_stream {
@@ -970,36 +980,32 @@ impl DirEntry {
     }
 
     #[cfg(any(
-        target_os = "linux",
+        target_os = "aix",
+        target_os = "android",
         target_os = "cygwin",
         target_os = "emscripten",
-        target_os = "android",
-        target_os = "solaris",
-        target_os = "illumos",
-        target_os = "haiku",
-        target_os = "l4re",
-        target_os = "fuchsia",
-        target_os = "redox",
-        target_os = "vxworks",
         target_os = "espidf",
+        target_os = "freebsd",
+        target_os = "fuchsia",
+        target_os = "haiku",
         target_os = "horizon",
-        target_os = "vita",
-        target_os = "aix",
-        target_os = "nto",
         target_os = "hurd",
+        target_os = "illumos",
+        target_os = "l4re",
+        target_os = "linux",
+        target_os = "nto",
+        target_os = "redox",
         target_os = "rtems",
+        target_os = "solaris",
+        target_os = "vita",
+        target_os = "vxworks",
         target_vendor = "apple",
     ))]
     pub fn ino(&self) -> u64 {
         self.entry.d_ino as u64
     }
 
-    #[cfg(any(
-        target_os = "freebsd",
-        target_os = "openbsd",
-        target_os = "netbsd",
-        target_os = "dragonfly"
-    ))]
+    #[cfg(any(target_os = "openbsd", target_os = "netbsd", target_os = "dragonfly"))]
     pub fn ino(&self) -> u64 {
         self.entry.d_fileno as u64
     }
@@ -1014,7 +1020,6 @@ impl DirEntry {
     #[cfg(any(
         target_os = "netbsd",
         target_os = "openbsd",
-        target_os = "freebsd",
         target_os = "dragonfly",
         target_vendor = "apple",
     ))]
@@ -1030,7 +1035,6 @@ impl DirEntry {
     #[cfg(not(any(
         target_os = "netbsd",
         target_os = "openbsd",
-        target_os = "freebsd",
         target_os = "dragonfly",
         target_vendor = "apple",
     )))]
@@ -1040,6 +1044,7 @@ impl DirEntry {
 
     #[cfg(not(any(
         target_os = "android",
+        target_os = "freebsd",
         target_os = "linux",
         target_os = "solaris",
         target_os = "illumos",
@@ -1055,6 +1060,7 @@ impl DirEntry {
     }
     #[cfg(any(
         target_os = "android",
+        target_os = "freebsd",
         target_os = "linux",
         target_os = "solaris",
         target_os = "illumos",
diff --git a/library/std/src/sys/fs/vexos.rs b/library/std/src/sys/fs/vexos.rs
new file mode 100644
index 00000000000..f642e7cb074
--- /dev/null
+++ b/library/std/src/sys/fs/vexos.rs
@@ -0,0 +1,615 @@
+use crate::ffi::{OsString, c_char};
+use crate::fmt;
+use crate::fs::TryLockError;
+use crate::hash::Hash;
+use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut, SeekFrom};
+use crate::path::{Path, PathBuf};
+use crate::sys::common::small_c_string::run_path_with_cstr;
+use crate::sys::time::SystemTime;
+use crate::sys::{unsupported, unsupported_err};
+
+#[expect(dead_code)]
+#[path = "unsupported.rs"]
+mod unsupported_fs;
+pub use unsupported_fs::{
+    DirBuilder, FileTimes, canonicalize, link, readlink, remove_dir_all, rename, rmdir, symlink,
+    unlink,
+};
+
+/// VEXos file descriptor.
+///
+/// This stores an opaque pointer to a [FatFs file object structure] managed by VEXos
+/// representing an open file on disk.
+///
+/// [FatFs file object structure]: https://github.com/Xilinx/embeddedsw/blob/master/lib/sw_services/xilffs/src/include/ff.h?rgh-link-date=2025-09-23T20%3A03%3A43Z#L215
+///
+/// # Safety
+///
+/// Since this platform uses a pointer to to an internal filesystem structure with a lifetime
+/// associated with it (rather than a UNIX-style file descriptor table), care must be taken to
+/// ensure that the pointer held by `FileDesc` is valid for as long as it exists.
+#[derive(Debug)]
+struct FileDesc(*mut vex_sdk::FIL);
+
+// SAFETY: VEXos's FDs can be used on a thread other than the one they were created on.
+unsafe impl Send for FileDesc {}
+// SAFETY: We assume an environment without threads (i.e. no RTOS).
+// (If there were threads, it is possible that a mutex would be required.)
+unsafe impl Sync for FileDesc {}
+
+pub struct File {
+    fd: FileDesc,
+}
+
+#[derive(Clone)]
+pub enum FileAttr {
+    Dir,
+    File { size: u64 },
+}
+
+pub struct ReadDir(!);
+
+pub struct DirEntry {
+    path: PathBuf,
+}
+
+#[derive(Clone, Debug)]
+pub struct OpenOptions {
+    read: bool,
+    write: bool,
+    append: bool,
+    truncate: bool,
+    create: bool,
+    create_new: bool,
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct FilePermissions {}
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
+pub struct FileType {
+    is_dir: bool,
+}
+
+impl FileAttr {
+    pub fn size(&self) -> u64 {
+        match self {
+            Self::File { size } => *size,
+            Self::Dir => 0,
+        }
+    }
+
+    pub fn perm(&self) -> FilePermissions {
+        FilePermissions {}
+    }
+
+    pub fn file_type(&self) -> FileType {
+        FileType { is_dir: matches!(self, FileAttr::Dir) }
+    }
+
+    pub fn modified(&self) -> io::Result<SystemTime> {
+        unsupported()
+    }
+
+    pub fn accessed(&self) -> io::Result<SystemTime> {
+        unsupported()
+    }
+
+    pub fn created(&self) -> io::Result<SystemTime> {
+        unsupported()
+    }
+}
+
+impl FilePermissions {
+    pub fn readonly(&self) -> bool {
+        false
+    }
+
+    pub fn set_readonly(&mut self, _readonly: bool) {
+        panic!("Perimissions do not exist")
+    }
+}
+
+impl FileType {
+    pub fn is_dir(&self) -> bool {
+        self.is_dir
+    }
+
+    pub fn is_file(&self) -> bool {
+        !self.is_dir
+    }
+
+    pub fn is_symlink(&self) -> bool {
+        // No symlinks in VEXos - entries are either files or directories.
+        false
+    }
+}
+
+impl fmt::Debug for ReadDir {
+    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0
+    }
+}
+
+impl Iterator for ReadDir {
+    type Item = io::Result<DirEntry>;
+
+    fn next(&mut self) -> Option<io::Result<DirEntry>> {
+        self.0
+    }
+}
+
+impl DirEntry {
+    pub fn path(&self) -> PathBuf {
+        self.path.clone()
+    }
+
+    pub fn file_name(&self) -> OsString {
+        self.path.file_name().unwrap_or_default().into()
+    }
+
+    pub fn metadata(&self) -> io::Result<FileAttr> {
+        stat(&self.path)
+    }
+
+    pub fn file_type(&self) -> io::Result<FileType> {
+        Ok(self.metadata()?.file_type())
+    }
+}
+
+impl OpenOptions {
+    pub fn new() -> OpenOptions {
+        OpenOptions {
+            read: false,
+            write: false,
+            append: false,
+            truncate: false,
+            create: false,
+            create_new: false,
+        }
+    }
+
+    pub fn read(&mut self, read: bool) {
+        self.read = read;
+    }
+    pub fn write(&mut self, write: bool) {
+        self.write = write;
+    }
+    pub fn append(&mut self, append: bool) {
+        self.append = append;
+    }
+    pub fn truncate(&mut self, truncate: bool) {
+        self.truncate = truncate;
+    }
+    pub fn create(&mut self, create: bool) {
+        self.create = create;
+    }
+    pub fn create_new(&mut self, create_new: bool) {
+        self.create_new = create_new;
+    }
+}
+
+impl File {
+    pub fn open(path: &Path, opts: &OpenOptions) -> io::Result<File> {
+        run_path_with_cstr(path, &|path| {
+            // Enforce the invariants of `create_new`/`create`.
+            //
+            // Since VEXos doesn't have anything akin to POSIX's `oflags`, we need to enforce
+            // the requirements that `create_new` can't have an existing file and `!create`
+            // doesn't create a file ourselves.
+            if !opts.read && (opts.write || opts.append) && (opts.create_new || !opts.create) {
+                let status = unsafe { vex_sdk::vexFileStatus(path.as_ptr()) };
+
+                if opts.create_new && status != 0 {
+                    return Err(io::const_error!(io::ErrorKind::AlreadyExists, "file exists",));
+                } else if !opts.create && status == 0 {
+                    return Err(io::const_error!(
+                        io::ErrorKind::NotFound,
+                        "no such file or directory",
+                    ));
+                }
+            }
+
+            let file = match opts {
+                // read + write - unsupported
+                OpenOptions { read: true, write: true, .. } => {
+                    return Err(io::const_error!(
+                        io::ErrorKind::InvalidInput,
+                        "opening files with read and write access is unsupported on this target",
+                    ));
+                }
+
+                // read
+                OpenOptions {
+                    read: true,
+                    write: false,
+                    append: _,
+                    truncate: false,
+                    create: false,
+                    create_new: false,
+                } => unsafe { vex_sdk::vexFileOpen(path.as_ptr(), c"".as_ptr()) },
+
+                // append
+                OpenOptions {
+                    read: false,
+                    write: _,
+                    append: true,
+                    truncate: false,
+                    create: _,
+                    create_new: _,
+                } => unsafe { vex_sdk::vexFileOpenWrite(path.as_ptr()) },
+
+                // write
+                OpenOptions {
+                    read: false,
+                    write: true,
+                    append: false,
+                    truncate,
+                    create: _,
+                    create_new: _,
+                } => unsafe {
+                    if *truncate {
+                        vex_sdk::vexFileOpenCreate(path.as_ptr())
+                    } else {
+                        // Open in append, but jump to the start of the file.
+                        let fd = vex_sdk::vexFileOpenWrite(path.as_ptr());
+                        vex_sdk::vexFileSeek(fd, 0, 0);
+                        fd
+                    }
+                },
+
+                _ => {
+                    return Err(io::const_error!(io::ErrorKind::InvalidInput, "invalid argument"));
+                }
+            };
+
+            if file.is_null() {
+                Err(io::const_error!(io::ErrorKind::NotFound, "could not open file"))
+            } else {
+                Ok(Self { fd: FileDesc(file) })
+            }
+        })
+    }
+
+    pub fn file_attr(&self) -> io::Result<FileAttr> {
+        // `vexFileSize` returns -1 upon error, so u64::try_from will fail on error.
+        if let Ok(size) = u64::try_from(unsafe {
+            // SAFETY: `self.fd` contains a valid pointer to `FIL` for this struct's lifetime.
+            vex_sdk::vexFileSize(self.fd.0)
+        }) {
+            Ok(FileAttr::File { size })
+        } else {
+            Err(io::const_error!(io::ErrorKind::InvalidData, "failed to get file size"))
+        }
+    }
+
+    pub fn fsync(&self) -> io::Result<()> {
+        self.flush()
+    }
+
+    pub fn datasync(&self) -> io::Result<()> {
+        self.flush()
+    }
+
+    pub fn lock(&self) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn lock_shared(&self) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn try_lock(&self) -> Result<(), TryLockError> {
+        Err(TryLockError::Error(unsupported_err()))
+    }
+
+    pub fn try_lock_shared(&self) -> Result<(), TryLockError> {
+        Err(TryLockError::Error(unsupported_err()))
+    }
+
+    pub fn unlock(&self) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn truncate(&self, _size: u64) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        let len = buf.len() as u32;
+        let buf_ptr = buf.as_mut_ptr();
+        let read = unsafe {
+            // SAFETY: `self.fd` contains a valid pointer to `FIL` for this struct's lifetime.
+            vex_sdk::vexFileRead(buf_ptr.cast::<c_char>(), 1, len, self.fd.0)
+        };
+
+        if read < 0 {
+            Err(io::const_error!(io::ErrorKind::Other, "could not read from file"))
+        } else {
+            Ok(read as usize)
+        }
+    }
+
+    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        crate::io::default_read_vectored(|b| self.read(b), bufs)
+    }
+
+    #[inline]
+    pub fn is_read_vectored(&self) -> bool {
+        false
+    }
+
+    pub fn read_buf(&self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
+        crate::io::default_read_buf(|b| self.read(b), cursor)
+    }
+
+    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
+        let len = buf.len() as u32;
+        let buf_ptr = buf.as_ptr();
+        let written = unsafe {
+            // SAFETY: `self.fd` contains a valid pointer to `FIL` for this struct's lifetime.
+            vex_sdk::vexFileWrite(buf_ptr.cast_mut().cast::<c_char>(), 1, len, self.fd.0)
+        };
+
+        if written < 0 {
+            Err(io::const_error!(io::ErrorKind::Other, "could not write to file"))
+        } else {
+            Ok(written as usize)
+        }
+    }
+
+    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        crate::io::default_write_vectored(|b| self.write(b), bufs)
+    }
+
+    #[inline]
+    pub fn is_write_vectored(&self) -> bool {
+        false
+    }
+
+    pub fn flush(&self) -> io::Result<()> {
+        unsafe {
+            // SAFETY: `self.fd` contains a valid pointer to `FIL` for this struct's lifetime.
+            vex_sdk::vexFileSync(self.fd.0);
+        }
+        Ok(())
+    }
+
+    pub fn tell(&self) -> io::Result<u64> {
+        // SAFETY: `self.fd` contains a valid pointer to `FIL` for this struct's lifetime.
+        let position = unsafe { vex_sdk::vexFileTell(self.fd.0) };
+
+        position.try_into().map_err(|_| {
+            io::const_error!(io::ErrorKind::InvalidData, "failed to get current location in file")
+        })
+    }
+
+    pub fn size(&self) -> Option<io::Result<u64>> {
+        None
+    }
+
+    pub fn seek(&self, pos: SeekFrom) -> io::Result<u64> {
+        const SEEK_SET: i32 = 0;
+        const SEEK_CUR: i32 = 1;
+        const SEEK_END: i32 = 2;
+
+        fn try_convert_offset<T: TryInto<u32>>(offset: T) -> io::Result<u32> {
+            offset.try_into().map_err(|_| {
+                io::const_error!(
+                    io::ErrorKind::InvalidInput,
+                    "cannot seek to an offset too large to fit in a 32 bit integer",
+                )
+            })
+        }
+
+        // SAFETY: `self.fd` contains a valid pointer to `FIL` for this struct's lifetime.
+        match pos {
+            SeekFrom::Start(offset) => unsafe {
+                map_fresult(vex_sdk::vexFileSeek(self.fd.0, try_convert_offset(offset)?, SEEK_SET))?
+            },
+            SeekFrom::End(offset) => unsafe {
+                if offset >= 0 {
+                    map_fresult(vex_sdk::vexFileSeek(
+                        self.fd.0,
+                        try_convert_offset(offset)?,
+                        SEEK_END,
+                    ))?
+                } else {
+                    // `vexFileSeek` does not support seeking with negative offset, meaning
+                    // we have to calculate the offset from the end of the file ourselves.
+
+                    // Seek to the end of the file to get the end position in the open buffer.
+                    map_fresult(vex_sdk::vexFileSeek(self.fd.0, 0, SEEK_END))?;
+                    let end_position = self.tell()?;
+
+                    map_fresult(vex_sdk::vexFileSeek(
+                        self.fd.0,
+                        // NOTE: Files internally use a 32-bit representation for stream
+                        // position, so `end_position as i64` should never overflow.
+                        try_convert_offset(end_position as i64 + offset)?,
+                        SEEK_SET,
+                    ))?
+                }
+            },
+            SeekFrom::Current(offset) => unsafe {
+                if offset >= 0 {
+                    map_fresult(vex_sdk::vexFileSeek(
+                        self.fd.0,
+                        try_convert_offset(offset)?,
+                        SEEK_CUR,
+                    ))?
+                } else {
+                    // `vexFileSeek` does not support seeking with negative offset, meaning
+                    // we have to calculate the offset from the stream position ourselves.
+                    map_fresult(vex_sdk::vexFileSeek(
+                        self.fd.0,
+                        try_convert_offset((self.tell()? as i64) + offset)?,
+                        SEEK_SET,
+                    ))?
+                }
+            },
+        }
+
+        Ok(self.tell()?)
+    }
+
+    pub fn duplicate(&self) -> io::Result<File> {
+        unsupported()
+    }
+
+    pub fn set_permissions(&self, _perm: FilePermissions) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn set_times(&self, _times: FileTimes) -> io::Result<()> {
+        unsupported()
+    }
+}
+
+impl fmt::Debug for File {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("File").field("fd", &self.fd.0).finish()
+    }
+}
+impl Drop for File {
+    fn drop(&mut self) {
+        unsafe { vex_sdk::vexFileClose(self.fd.0) };
+    }
+}
+
+pub fn readdir(_p: &Path) -> io::Result<ReadDir> {
+    // While there *is* a userspace function for reading file directories,
+    // the necessary implementation cannot currently be done cleanly, as
+    // VEXos does not expose directory length to user programs.
+    //
+    // This means that we would need to create a large fixed-length buffer
+    // and hope that the folder's contents didn't exceed that buffer's length,
+    // which obviously isn't behavior we want to rely on in the standard library.
+    unsupported()
+}
+
+pub fn set_perm(_p: &Path, _perm: FilePermissions) -> io::Result<()> {
+    unsupported()
+}
+
+pub fn exists(path: &Path) -> io::Result<bool> {
+    run_path_with_cstr(path, &|path| Ok(unsafe { vex_sdk::vexFileStatus(path.as_ptr()) } != 0))
+}
+
+pub fn stat(p: &Path) -> io::Result<FileAttr> {
+    // `vexFileStatus` returns 3 if the given path is a directory, 1 if the path is a
+    // file, or 0 if no such path exists.
+    const FILE_STATUS_DIR: u32 = 3;
+
+    run_path_with_cstr(p, &|c_path| {
+        let file_type = unsafe { vex_sdk::vexFileStatus(c_path.as_ptr()) };
+
+        // We can't get the size if its a directory because we cant open it as a file
+        if file_type == FILE_STATUS_DIR {
+            Ok(FileAttr::Dir)
+        } else {
+            let mut opts = OpenOptions::new();
+            opts.read(true);
+            let file = File::open(p, &opts)?;
+            file.file_attr()
+        }
+    })
+}
+
+pub fn lstat(p: &Path) -> io::Result<FileAttr> {
+    // Symlinks aren't supported in this filesystem
+    stat(p)
+}
+
+// Cannot use `copy` from `common` here, since `File::set_permissions` is unsupported on this target.
+pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
+    use crate::fs::File;
+
+    // NOTE: If `from` is a directory, this call should fail due to vexFileOpen* returning null.
+    let mut reader = File::open(from)?;
+    let mut writer = File::create(to)?;
+
+    io::copy(&mut reader, &mut writer)
+}
+
+fn map_fresult(fresult: vex_sdk::FRESULT) -> io::Result<()> {
+    // VEX uses a derivative of FatFs (Xilinx's xilffs library) for filesystem operations.
+    match fresult {
+        vex_sdk::FRESULT::FR_OK => Ok(()),
+        vex_sdk::FRESULT::FR_DISK_ERR => Err(io::const_error!(
+            io::ErrorKind::Uncategorized,
+            "internal function reported an unrecoverable hard error",
+        )),
+        vex_sdk::FRESULT::FR_INT_ERR => Err(io::const_error!(
+            io::ErrorKind::Uncategorized,
+            "internal error in filesystem runtime",
+        )),
+        vex_sdk::FRESULT::FR_NOT_READY => Err(io::const_error!(
+            io::ErrorKind::Uncategorized,
+            "the storage device could not be prepared to work",
+        )),
+        vex_sdk::FRESULT::FR_NO_FILE => Err(io::const_error!(
+            io::ErrorKind::NotFound,
+            "could not find the file in the directory"
+        )),
+        vex_sdk::FRESULT::FR_NO_PATH => Err(io::const_error!(
+            io::ErrorKind::NotFound,
+            "a directory in the path name could not be found",
+        )),
+        vex_sdk::FRESULT::FR_INVALID_NAME => Err(io::const_error!(
+            io::ErrorKind::InvalidInput,
+            "the given string is invalid as a path name",
+        )),
+        vex_sdk::FRESULT::FR_DENIED => Err(io::const_error!(
+            io::ErrorKind::PermissionDenied,
+            "the required access for this operation was denied",
+        )),
+        vex_sdk::FRESULT::FR_EXIST => Err(io::const_error!(
+            io::ErrorKind::AlreadyExists,
+            "an object with the same name already exists in the directory",
+        )),
+        vex_sdk::FRESULT::FR_INVALID_OBJECT => Err(io::const_error!(
+            io::ErrorKind::Uncategorized,
+            "invalid or null file/directory object",
+        )),
+        vex_sdk::FRESULT::FR_WRITE_PROTECTED => Err(io::const_error!(
+            io::ErrorKind::PermissionDenied,
+            "a write operation was performed on write-protected media",
+        )),
+        vex_sdk::FRESULT::FR_INVALID_DRIVE => Err(io::const_error!(
+            io::ErrorKind::InvalidInput,
+            "an invalid drive number was specified in the path name",
+        )),
+        vex_sdk::FRESULT::FR_NOT_ENABLED => Err(io::const_error!(
+            io::ErrorKind::Uncategorized,
+            "work area for the logical drive has not been registered",
+        )),
+        vex_sdk::FRESULT::FR_NO_FILESYSTEM => Err(io::const_error!(
+            io::ErrorKind::Uncategorized,
+            "valid FAT volume could not be found on the drive",
+        )),
+        vex_sdk::FRESULT::FR_MKFS_ABORTED => Err(io::const_error!(
+            io::ErrorKind::Uncategorized,
+            "failed to create filesystem volume"
+        )),
+        vex_sdk::FRESULT::FR_TIMEOUT => Err(io::const_error!(
+            io::ErrorKind::TimedOut,
+            "the function was canceled due to a timeout of thread-safe control",
+        )),
+        vex_sdk::FRESULT::FR_LOCKED => Err(io::const_error!(
+            io::ErrorKind::Uncategorized,
+            "the operation to the object was rejected by file sharing control",
+        )),
+        vex_sdk::FRESULT::FR_NOT_ENOUGH_CORE => {
+            Err(io::const_error!(io::ErrorKind::OutOfMemory, "not enough memory for the operation"))
+        }
+        vex_sdk::FRESULT::FR_TOO_MANY_OPEN_FILES => Err(io::const_error!(
+            io::ErrorKind::Uncategorized,
+            "maximum number of open files has been reached",
+        )),
+        vex_sdk::FRESULT::FR_INVALID_PARAMETER => {
+            Err(io::const_error!(io::ErrorKind::InvalidInput, "a given parameter was invalid"))
+        }
+        _ => unreachable!(), // C-style enum
+    }
+}
diff --git a/library/std/src/sys/fs/wasi.rs b/library/std/src/sys/fs/wasi.rs
index b65d86de12a..0b65b9cb389 100644
--- a/library/std/src/sys/fs/wasi.rs
+++ b/library/std/src/sys/fs/wasi.rs
@@ -848,7 +848,14 @@ fn remove_dir_all_recursive(parent: &WasiFd, path: &Path) -> io::Result<()> {
 
     // Iterate over all the entries in this directory, and travel recursively if
     // necessary
-    for entry in ReadDir::new(fd, dummy_root) {
+    //
+    // Note that all directory entries for this directory are read first before
+    // any removal is done. This works around the fact that the WASIp1 API for
+    // reading directories is not well-designed for handling mutations between
+    // invocations of reading a directory. By reading all the entries at once
+    // this ensures that, at least without concurrent modifications, it should
+    // be possible to delete everything.
+    for entry in ReadDir::new(fd, dummy_root).collect::<Vec<_>>() {
         let entry = entry?;
         let path = crate::str::from_utf8(&entry.name).map_err(|_| {
             io::const_error!(io::ErrorKind::Uncategorized, "invalid utf-8 file name found")
diff --git a/library/std/src/sys/mod.rs b/library/std/src/sys/mod.rs
index 8c115015580..2dbdc8a4e02 100644
--- a/library/std/src/sys/mod.rs
+++ b/library/std/src/sys/mod.rs
@@ -31,6 +31,7 @@ pub mod process;
 pub mod random;
 pub mod stdio;
 pub mod sync;
+pub mod thread;
 pub mod thread_local;
 
 // FIXME(117276): remove this, move feature implementations into individual
diff --git a/library/std/src/sys/net/connection/sgx.rs b/library/std/src/sys/net/connection/sgx.rs
index 9b54571997d..8c9c17d3f17 100644
--- a/library/std/src/sys/net/connection/sgx.rs
+++ b/library/std/src/sys/net/connection/sgx.rs
@@ -499,16 +499,6 @@ impl fmt::Display for NonIpSockAddr {
 
 pub struct LookupHost(!);
 
-impl LookupHost {
-    fn new(host: String) -> io::Result<LookupHost> {
-        Err(io::Error::new(io::ErrorKind::Uncategorized, NonIpSockAddr { host }))
-    }
-
-    pub fn port(&self) -> u16 {
-        self.0
-    }
-}
-
 impl Iterator for LookupHost {
     type Item = SocketAddr;
     fn next(&mut self) -> Option<SocketAddr> {
@@ -516,18 +506,9 @@ impl Iterator for LookupHost {
     }
 }
 
-impl TryFrom<&str> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from(v: &str) -> io::Result<LookupHost> {
-        LookupHost::new(v.to_owned())
-    }
-}
-
-impl<'a> TryFrom<(&'a str, u16)> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from((host, port): (&'a str, u16)) -> io::Result<LookupHost> {
-        LookupHost::new(format!("{host}:{port}"))
-    }
+pub fn lookup_host(host: &str, port: u16) -> io::Result<LookupHost> {
+    Err(io::Error::new(
+        io::ErrorKind::Uncategorized,
+        NonIpSockAddr { host: format!("{host}:{port}") },
+    ))
 }
diff --git a/library/std/src/sys/net/connection/socket/hermit.rs b/library/std/src/sys/net/connection/socket/hermit.rs
index f49821657d9..5200eaa5786 100644
--- a/library/std/src/sys/net/connection/socket/hermit.rs
+++ b/library/std/src/sys/net/connection/socket/hermit.rs
@@ -304,7 +304,8 @@ impl Socket {
     }
 
     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
-        unimplemented!()
+        let raw: c_int = getsockopt(self, libc::SOL_SOCKET, libc::SO_ERROR)?;
+        if raw == 0 { Ok(None) } else { Ok(Some(io::Error::from_raw_os_error(raw as i32))) }
     }
 
     // This is used by sys_common code to abstract over Windows and Unix.
diff --git a/library/std/src/sys/net/connection/socket/mod.rs b/library/std/src/sys/net/connection/socket/mod.rs
index 564f2e3a01f..1dd06e97bba 100644
--- a/library/std/src/sys/net/connection/socket/mod.rs
+++ b/library/std/src/sys/net/connection/socket/mod.rs
@@ -258,7 +258,7 @@ fn to_ipv6mr_interface(value: u32) -> crate::ffi::c_uint {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// get_host_addresses
+// lookup_host
 ////////////////////////////////////////////////////////////////////////////////
 
 pub struct LookupHost {
@@ -267,12 +267,6 @@ pub struct LookupHost {
     port: u16,
 }
 
-impl LookupHost {
-    pub fn port(&self) -> u16 {
-        self.port
-    }
-}
-
 impl Iterator for LookupHost {
     type Item = SocketAddr;
     fn next(&mut self) -> Option<SocketAddr> {
@@ -281,7 +275,10 @@ impl Iterator for LookupHost {
                 let cur = self.cur.as_ref()?;
                 self.cur = cur.ai_next;
                 match socket_addr_from_c(cur.ai_addr.cast(), cur.ai_addrlen as usize) {
-                    Ok(addr) => return Some(addr),
+                    Ok(mut addr) => {
+                        addr.set_port(self.port);
+                        return Some(addr);
+                    }
                     Err(_) => continue,
                 }
             }
@@ -298,42 +295,17 @@ impl Drop for LookupHost {
     }
 }
 
-impl TryFrom<&str> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from(s: &str) -> io::Result<LookupHost> {
-        macro_rules! try_opt {
-            ($e:expr, $msg:expr) => {
-                match $e {
-                    Some(r) => r,
-                    None => return Err(io::const_error!(io::ErrorKind::InvalidInput, $msg)),
-                }
-            };
+pub fn lookup_host(host: &str, port: u16) -> io::Result<LookupHost> {
+    init();
+    run_with_cstr(host.as_bytes(), &|c_host| {
+        let mut hints: c::addrinfo = unsafe { mem::zeroed() };
+        hints.ai_socktype = c::SOCK_STREAM;
+        let mut res = ptr::null_mut();
+        unsafe {
+            cvt_gai(c::getaddrinfo(c_host.as_ptr(), ptr::null(), &hints, &mut res))
+                .map(|_| LookupHost { original: res, cur: res, port })
         }
-
-        // split the string by ':' and convert the second part to u16
-        let (host, port_str) = try_opt!(s.rsplit_once(':'), "invalid socket address");
-        let port: u16 = try_opt!(port_str.parse().ok(), "invalid port value");
-        (host, port).try_into()
-    }
-}
-
-impl<'a> TryFrom<(&'a str, u16)> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from((host, port): (&'a str, u16)) -> io::Result<LookupHost> {
-        init();
-
-        run_with_cstr(host.as_bytes(), &|c_host| {
-            let mut hints: c::addrinfo = unsafe { mem::zeroed() };
-            hints.ai_socktype = c::SOCK_STREAM;
-            let mut res = ptr::null_mut();
-            unsafe {
-                cvt_gai(c::getaddrinfo(c_host.as_ptr(), ptr::null(), &hints, &mut res))
-                    .map(|_| LookupHost { original: res, cur: res, port })
-            }
-        })
-    }
+    })
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/library/std/src/sys/net/connection/socket/tests.rs b/library/std/src/sys/net/connection/socket/tests.rs
index fc236b8027b..049355afca7 100644
--- a/library/std/src/sys/net/connection/socket/tests.rs
+++ b/library/std/src/sys/net/connection/socket/tests.rs
@@ -4,7 +4,7 @@ use crate::collections::HashMap;
 #[test]
 fn no_lookup_host_duplicates() {
     let mut addrs = HashMap::new();
-    let lh = match LookupHost::try_from(("localhost", 0)) {
+    let lh = match lookup_host("localhost", 0) {
         Ok(lh) => lh,
         Err(e) => panic!("couldn't resolve `localhost`: {e}"),
     };
diff --git a/library/std/src/sys/net/connection/socket/unix.rs b/library/std/src/sys/net/connection/socket/unix.rs
index 8216f8d2fd5..a191576d93b 100644
--- a/library/std/src/sys/net/connection/socket/unix.rs
+++ b/library/std/src/sys/net/connection/socket/unix.rs
@@ -485,14 +485,15 @@ impl Socket {
 
     // bionic libc makes no use of this flag
     #[cfg(target_os = "linux")]
-    pub fn set_deferaccept(&self, accept: u32) -> io::Result<()> {
-        setsockopt(self, libc::IPPROTO_TCP, libc::TCP_DEFER_ACCEPT, accept as c_int)
+    pub fn set_deferaccept(&self, accept: Duration) -> io::Result<()> {
+        let val = cmp::min(accept.as_secs(), c_int::MAX as u64) as c_int;
+        setsockopt(self, libc::IPPROTO_TCP, libc::TCP_DEFER_ACCEPT, val)
     }
 
     #[cfg(target_os = "linux")]
-    pub fn deferaccept(&self) -> io::Result<u32> {
+    pub fn deferaccept(&self) -> io::Result<Duration> {
         let raw: c_int = getsockopt(self, libc::IPPROTO_TCP, libc::TCP_DEFER_ACCEPT)?;
-        Ok(raw as u32)
+        Ok(Duration::from_secs(raw as _))
     }
 
     #[cfg(any(target_os = "freebsd", target_os = "netbsd"))]
diff --git a/library/std/src/sys/net/connection/socket/windows.rs b/library/std/src/sys/net/connection/socket/windows.rs
index b71d8b1357b..5b6f4cedf1b 100644
--- a/library/std/src/sys/net/connection/socket/windows.rs
+++ b/library/std/src/sys/net/connection/socket/windows.rs
@@ -8,9 +8,8 @@ use crate::net::{Shutdown, SocketAddr};
 use crate::os::windows::io::{
     AsRawSocket, AsSocket, BorrowedSocket, FromRawSocket, IntoRawSocket, OwnedSocket, RawSocket,
 };
-use crate::sync::atomic::Atomic;
-use crate::sync::atomic::Ordering::{AcqRel, Relaxed};
 use crate::sys::c;
+use crate::sys::pal::winsock::last_error;
 use crate::sys_common::{AsInner, FromInner, IntoInner};
 use crate::time::Duration;
 use crate::{cmp, mem, ptr, sys};
@@ -112,84 +111,11 @@ pub(super) mod netc {
     }
 }
 
+pub use crate::sys::pal::winsock::{cleanup, cvt, cvt_gai, cvt_r, startup as init};
+
 #[expect(missing_debug_implementations)]
 pub struct Socket(OwnedSocket);
 
-static WSA_INITIALIZED: Atomic<bool> = Atomic::<bool>::new(false);
-
-/// Checks whether the Windows socket interface has been started already, and
-/// if not, starts it.
-#[inline]
-pub fn init() {
-    if !WSA_INITIALIZED.load(Relaxed) {
-        wsa_startup();
-    }
-}
-
-#[cold]
-fn wsa_startup() {
-    unsafe {
-        let mut data: c::WSADATA = mem::zeroed();
-        let ret = c::WSAStartup(
-            0x202, // version 2.2
-            &mut data,
-        );
-        assert_eq!(ret, 0);
-        if WSA_INITIALIZED.swap(true, AcqRel) {
-            // If another thread raced with us and called WSAStartup first then call
-            // WSACleanup so it's as though WSAStartup was only called once.
-            c::WSACleanup();
-        }
-    }
-}
-
-pub fn cleanup() {
-    // We don't need to call WSACleanup here because exiting the process will cause
-    // the OS to clean everything for us, which is faster than doing it manually.
-    // See #141799.
-}
-
-/// Returns the last error from the Windows socket interface.
-fn last_error() -> io::Error {
-    io::Error::from_raw_os_error(unsafe { c::WSAGetLastError() })
-}
-
-#[doc(hidden)]
-pub trait IsMinusOne {
-    fn is_minus_one(&self) -> bool;
-}
-
-macro_rules! impl_is_minus_one {
-    ($($t:ident)*) => ($(impl IsMinusOne for $t {
-        fn is_minus_one(&self) -> bool {
-            *self == -1
-        }
-    })*)
-}
-
-impl_is_minus_one! { i8 i16 i32 i64 isize }
-
-/// Checks if the signed integer is the Windows constant `SOCKET_ERROR` (-1)
-/// and if so, returns the last error from the Windows socket interface. This
-/// function must be called before another call to the socket API is made.
-pub fn cvt<T: IsMinusOne>(t: T) -> io::Result<T> {
-    if t.is_minus_one() { Err(last_error()) } else { Ok(t) }
-}
-
-/// A variant of `cvt` for `getaddrinfo` which return 0 for a success.
-pub fn cvt_gai(err: c_int) -> io::Result<()> {
-    if err == 0 { Ok(()) } else { Err(last_error()) }
-}
-
-/// Just to provide the same interface as sys/pal/unix/net.rs
-pub fn cvt_r<T, F>(mut f: F) -> io::Result<T>
-where
-    T: IsMinusOne,
-    F: FnMut() -> T,
-{
-    cvt(f())
-}
-
 impl Socket {
     pub fn new(addr: &SocketAddr, ty: c_int) -> io::Result<Socket> {
         let family = match *addr {
diff --git a/library/std/src/sys/net/connection/uefi/mod.rs b/library/std/src/sys/net/connection/uefi/mod.rs
index 00368042873..004f6d413a1 100644
--- a/library/std/src/sys/net/connection/uefi/mod.rs
+++ b/library/std/src/sys/net/connection/uefi/mod.rs
@@ -333,12 +333,6 @@ impl fmt::Debug for UdpSocket {
 
 pub struct LookupHost(!);
 
-impl LookupHost {
-    pub fn port(&self) -> u16 {
-        self.0
-    }
-}
-
 impl Iterator for LookupHost {
     type Item = SocketAddr;
     fn next(&mut self) -> Option<SocketAddr> {
@@ -346,18 +340,6 @@ impl Iterator for LookupHost {
     }
 }
 
-impl TryFrom<&str> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from(_v: &str) -> io::Result<LookupHost> {
-        unsupported()
-    }
-}
-
-impl<'a> TryFrom<(&'a str, u16)> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from(_v: (&'a str, u16)) -> io::Result<LookupHost> {
-        unsupported()
-    }
+pub fn lookup_host(_host: &str, _port: u16) -> io::Result<LookupHost> {
+    unsupported()
 }
diff --git a/library/std/src/sys/net/connection/unsupported.rs b/library/std/src/sys/net/connection/unsupported.rs
index fbc86343272..fb18e8dec55 100644
--- a/library/std/src/sys/net/connection/unsupported.rs
+++ b/library/std/src/sys/net/connection/unsupported.rs
@@ -304,12 +304,6 @@ impl fmt::Debug for UdpSocket {
 
 pub struct LookupHost(!);
 
-impl LookupHost {
-    pub fn port(&self) -> u16 {
-        self.0
-    }
-}
-
 impl Iterator for LookupHost {
     type Item = SocketAddr;
     fn next(&mut self) -> Option<SocketAddr> {
@@ -317,18 +311,6 @@ impl Iterator for LookupHost {
     }
 }
 
-impl TryFrom<&str> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from(_v: &str) -> io::Result<LookupHost> {
-        unsupported()
-    }
-}
-
-impl<'a> TryFrom<(&'a str, u16)> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from(_v: (&'a str, u16)) -> io::Result<LookupHost> {
-        unsupported()
-    }
+pub fn lookup_host(_host: &str, _port: u16) -> io::Result<LookupHost> {
+    unsupported()
 }
diff --git a/library/std/src/sys/net/connection/wasip1.rs b/library/std/src/sys/net/connection/wasip1.rs
index cdfa25c8a44..048dafdcd7f 100644
--- a/library/std/src/sys/net/connection/wasip1.rs
+++ b/library/std/src/sys/net/connection/wasip1.rs
@@ -477,12 +477,6 @@ impl fmt::Debug for UdpSocket {
 
 pub struct LookupHost(!);
 
-impl LookupHost {
-    pub fn port(&self) -> u16 {
-        self.0
-    }
-}
-
 impl Iterator for LookupHost {
     type Item = SocketAddr;
     fn next(&mut self) -> Option<SocketAddr> {
@@ -490,18 +484,6 @@ impl Iterator for LookupHost {
     }
 }
 
-impl<'a> TryFrom<&'a str> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from(_v: &'a str) -> io::Result<LookupHost> {
-        unsupported()
-    }
-}
-
-impl<'a> TryFrom<(&'a str, u16)> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from(_v: (&'a str, u16)) -> io::Result<LookupHost> {
-        unsupported()
-    }
+pub fn lookup_host(_host: &str, _port: u16) -> io::Result<LookupHost> {
+    unsupported()
 }
diff --git a/library/std/src/sys/net/connection/xous/dns.rs b/library/std/src/sys/net/connection/xous/dns.rs
index bb29d211fad..b139376f597 100644
--- a/library/std/src/sys/net/connection/xous/dns.rs
+++ b/library/std/src/sys/net/connection/xous/dns.rs
@@ -1,15 +1,8 @@
-use core::convert::{TryFrom, TryInto};
-
 use crate::io;
 use crate::net::{Ipv4Addr, SocketAddr, SocketAddrV4, SocketAddrV6};
 use crate::os::xous::ffi::lend_mut;
 use crate::os::xous::services::{DnsLendMut, dns_server};
 
-pub struct DnsError {
-    #[allow(dead_code)]
-    pub code: u8,
-}
-
 #[repr(C, align(4096))]
 struct LookupHostQuery([u8; 4096]);
 
@@ -20,12 +13,6 @@ pub struct LookupHost {
     count: usize,
 }
 
-impl LookupHost {
-    pub fn port(&self) -> u16 {
-        self.port
-    }
-}
-
 impl Iterator for LookupHost {
     type Item = SocketAddr;
     fn next(&mut self) -> Option<SocketAddr> {
@@ -72,7 +59,7 @@ impl Iterator for LookupHost {
     }
 }
 
-pub fn lookup(query: &str, port: u16) -> Result<LookupHost, DnsError> {
+pub fn lookup_host(query: &str, port: u16) -> io::Result<LookupHost> {
     let mut result = LookupHost { data: LookupHostQuery([0u8; 4096]), offset: 0, count: 0, port };
 
     // Copy the query into the message that gets sent to the DNS server
@@ -89,7 +76,7 @@ pub fn lookup(query: &str, port: u16) -> Result<LookupHost, DnsError> {
     )
     .unwrap();
     if result.data.0[0] != 0 {
-        return Err(DnsError { code: result.data.0[1] });
+        return Err(io::const_error!(io::ErrorKind::InvalidInput, "DNS failure"));
     }
     assert_eq!(result.offset, 0);
     result.count = result.data.0[1] as usize;
@@ -98,31 +85,3 @@ pub fn lookup(query: &str, port: u16) -> Result<LookupHost, DnsError> {
     result.offset = 2;
     Ok(result)
 }
-
-impl TryFrom<&str> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from(s: &str) -> io::Result<LookupHost> {
-        macro_rules! try_opt {
-            ($e:expr, $msg:expr) => {
-                match $e {
-                    Some(r) => r,
-                    None => return Err(io::const_error!(io::ErrorKind::InvalidInput, &$msg)),
-                }
-            };
-        }
-
-        // split the string by ':' and convert the second part to u16
-        let (host, port_str) = try_opt!(s.rsplit_once(':'), "invalid socket address");
-        let port: u16 = try_opt!(port_str.parse().ok(), "invalid port value");
-        (host, port).try_into()
-    }
-}
-
-impl TryFrom<(&str, u16)> for LookupHost {
-    type Error = io::Error;
-
-    fn try_from(v: (&str, u16)) -> io::Result<LookupHost> {
-        lookup(v.0, v.1).map_err(|_e| io::const_error!(io::ErrorKind::InvalidInput, "DNS failure"))
-    }
-}
diff --git a/library/std/src/sys/net/connection/xous/mod.rs b/library/std/src/sys/net/connection/xous/mod.rs
index e44a375b9e3..0f77be5c3fa 100644
--- a/library/std/src/sys/net/connection/xous/mod.rs
+++ b/library/std/src/sys/net/connection/xous/mod.rs
@@ -45,4 +45,4 @@ pub struct GetAddress {
     raw: [u8; 4096],
 }
 
-pub use dns::LookupHost;
+pub use dns::lookup_host;
diff --git a/library/std/src/sys/net/hostname/mod.rs b/library/std/src/sys/net/hostname/mod.rs
new file mode 100644
index 00000000000..8ffe4894d71
--- /dev/null
+++ b/library/std/src/sys/net/hostname/mod.rs
@@ -0,0 +1,14 @@
+cfg_select! {
+    all(target_family = "unix", not(target_os = "espidf")) => {
+        mod unix;
+        pub use unix::hostname;
+    }
+    target_os = "windows" => {
+        mod windows;
+        pub use windows::hostname;
+    }
+    _ => {
+        mod unsupported;
+        pub use unsupported::hostname;
+    }
+}
diff --git a/library/std/src/sys/net/hostname/unix.rs b/library/std/src/sys/net/hostname/unix.rs
new file mode 100644
index 00000000000..bc6fa82a38f
--- /dev/null
+++ b/library/std/src/sys/net/hostname/unix.rs
@@ -0,0 +1,62 @@
+use crate::ffi::OsString;
+use crate::io;
+use crate::os::unix::ffi::OsStringExt;
+use crate::sys::pal::os::errno;
+
+pub fn hostname() -> io::Result<OsString> {
+    // Query the system for the maximum host name length.
+    let host_name_max = match unsafe { libc::sysconf(libc::_SC_HOST_NAME_MAX) } {
+        // If this fails (possibly because there is no maximum length), then
+        // assume a maximum length of _POSIX_HOST_NAME_MAX (255).
+        -1 => 255,
+        max => max as usize,
+    };
+
+    // Reserve space for the nul terminator too.
+    let mut buf = Vec::<u8>::try_with_capacity(host_name_max + 1)?;
+    loop {
+        // SAFETY: `buf.capacity()` bytes of `buf` are writable.
+        let r = unsafe { libc::gethostname(buf.as_mut_ptr().cast(), buf.capacity()) };
+        match (r != 0).then(errno) {
+            None => {
+                // Unfortunately, the UNIX specification says that the name will
+                // be truncated if it does not fit in the buffer, without returning
+                // an error. As additionally, the truncated name may still be null-
+                // terminated, there is no reliable way to  detect truncation.
+                // Fortunately, most platforms ignore what the specification says
+                // and return an error (mostly ENAMETOOLONG). Should that not be
+                // the case, the following detects truncation if the null-terminator
+                // was omitted. Note that this check does not impact performance at
+                // all as we need to find the length of the string anyways.
+                //
+                // Use `strnlen` as it does not place an initialization requirement
+                // on the bytes after the nul terminator.
+                //
+                // SAFETY: `buf.capacity()` bytes of `buf` are accessible, and are
+                // initialized up to and including a possible nul terminator.
+                let len = unsafe { libc::strnlen(buf.as_ptr().cast(), buf.capacity()) };
+                if len < buf.capacity() {
+                    // If the string is nul-terminated, we assume that is has not
+                    // been truncated, as the capacity *should be* enough to hold
+                    // `HOST_NAME_MAX` bytes.
+                    // SAFETY: `len + 1` bytes have been initialized (we exclude
+                    // the nul terminator from the string).
+                    unsafe { buf.set_len(len) };
+                    return Ok(OsString::from_vec(buf));
+                }
+            }
+            // As `buf.capacity()` is always less than or equal to `isize::MAX`
+            // (Rust allocations cannot exceed that limit), the only way `EINVAL`
+            // can be returned is if the system uses `EINVAL` to report that the
+            // name does not fit in the provided buffer. In that case (or in the
+            // case of `ENAMETOOLONG`), resize the buffer and try again.
+            Some(libc::EINVAL | libc::ENAMETOOLONG) => {}
+            // Other error codes (e.g. EPERM) have nothing to do with the buffer
+            // size and should be returned to the user.
+            Some(err) => return Err(io::Error::from_raw_os_error(err)),
+        }
+
+        // Resize the buffer (according to `Vec`'s resizing rules) and try again.
+        buf.try_reserve(buf.capacity() + 1)?;
+    }
+}
diff --git a/library/std/src/sys/net/hostname/unsupported.rs b/library/std/src/sys/net/hostname/unsupported.rs
new file mode 100644
index 00000000000..d868f68f32d
--- /dev/null
+++ b/library/std/src/sys/net/hostname/unsupported.rs
@@ -0,0 +1,6 @@
+use crate::ffi::OsString;
+use crate::io::{Error, Result};
+
+pub fn hostname() -> Result<OsString> {
+    Err(Error::UNSUPPORTED_PLATFORM)
+}
diff --git a/library/std/src/sys/net/hostname/windows.rs b/library/std/src/sys/net/hostname/windows.rs
new file mode 100644
index 00000000000..24eed100f32
--- /dev/null
+++ b/library/std/src/sys/net/hostname/windows.rs
@@ -0,0 +1,24 @@
+use crate::ffi::OsString;
+use crate::io::Result;
+use crate::mem::MaybeUninit;
+use crate::os::windows::ffi::OsStringExt;
+use crate::sys::pal::c;
+use crate::sys::pal::winsock::{self, cvt};
+
+pub fn hostname() -> Result<OsString> {
+    winsock::startup();
+
+    // The documentation of GetHostNameW says that a buffer size of 256 is
+    // always enough.
+    let mut buffer = [const { MaybeUninit::<u16>::uninit() }; 256];
+    // SAFETY: these parameters specify a valid, writable region of memory.
+    cvt(unsafe { c::GetHostNameW(buffer.as_mut_ptr().cast(), buffer.len() as i32) })?;
+    // Use `lstrlenW` here as it does not require the bytes after the nul
+    // terminator to be initialized.
+    // SAFETY: if `GetHostNameW` returns successfully, the name is nul-terminated.
+    let len = unsafe { c::lstrlenW(buffer.as_ptr().cast()) };
+    // SAFETY: the length of the name is `len`, hence `len` bytes have been
+    //         initialized by `GetHostNameW`.
+    let name = unsafe { buffer[..len as usize].assume_init_ref() };
+    Ok(OsString::from_wide(name))
+}
diff --git a/library/std/src/sys/net/mod.rs b/library/std/src/sys/net/mod.rs
index dffc4ea7f81..bfe5cf53128 100644
--- a/library/std/src/sys/net/mod.rs
+++ b/library/std/src/sys/net/mod.rs
@@ -2,3 +2,6 @@
 /// `UdpSocket` as well as related functionality like DNS resolving.
 mod connection;
 pub use connection::*;
+
+mod hostname;
+pub use hostname::hostname;
diff --git a/library/std/src/sys/pal/hermit/mod.rs b/library/std/src/sys/pal/hermit/mod.rs
index fb8d69b7375..3ddf6e5acb0 100644
--- a/library/std/src/sys/pal/hermit/mod.rs
+++ b/library/std/src/sys/pal/hermit/mod.rs
@@ -25,7 +25,6 @@ pub mod futex;
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
-pub mod thread;
 pub mod time;
 
 pub fn unsupported<T>() -> crate::io::Result<T> {
diff --git a/library/std/src/sys/pal/hermit/os.rs b/library/std/src/sys/pal/hermit/os.rs
index 0fe713a503b..9681964ed9b 100644
--- a/library/std/src/sys/pal/hermit/os.rs
+++ b/library/std/src/sys/pal/hermit/os.rs
@@ -3,7 +3,7 @@ use crate::ffi::{OsStr, OsString};
 use crate::marker::PhantomData;
 use crate::path::{self, PathBuf};
 use crate::sys::unsupported;
-use crate::{fmt, io, str};
+use crate::{fmt, io};
 
 pub fn errno() -> i32 {
     unsafe { hermit_abi::get_errno() }
diff --git a/library/std/src/sys/pal/hermit/time.rs b/library/std/src/sys/pal/hermit/time.rs
index 89a427ab88b..bd6fd5a3de4 100644
--- a/library/std/src/sys/pal/hermit/time.rs
+++ b/library/std/src/sys/pal/hermit/time.rs
@@ -25,23 +25,23 @@ impl Timespec {
         Timespec { t: timespec { tv_sec, tv_nsec } }
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    const fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
-        // FIXME: const PartialOrd
-        let mut cmp = self.t.tv_sec - other.t.tv_sec;
-        if cmp == 0 {
-            cmp = self.t.tv_nsec as i64 - other.t.tv_nsec as i64;
+    fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
+        fn sub_ge_to_unsigned(a: i64, b: i64) -> u64 {
+            debug_assert!(a >= b);
+            a.wrapping_sub(b).cast_unsigned()
         }
 
-        if cmp >= 0 {
+        if self >= other {
+            // Logic here is identical to Unix version of `Timestamp::sub_timespec`,
+            // check comments there why operations do not overflow.
             Ok(if self.t.tv_nsec >= other.t.tv_nsec {
                 Duration::new(
-                    (self.t.tv_sec - other.t.tv_sec) as u64,
+                    sub_ge_to_unsigned(self.t.tv_sec, other.t.tv_sec),
                     (self.t.tv_nsec - other.t.tv_nsec) as u32,
                 )
             } else {
                 Duration::new(
-                    (self.t.tv_sec - 1 - other.t.tv_sec) as u64,
+                    sub_ge_to_unsigned(self.t.tv_sec - 1, other.t.tv_sec),
                     (self.t.tv_nsec + NSEC_PER_SEC - other.t.tv_nsec) as u32,
                 )
             })
@@ -53,22 +53,20 @@ impl Timespec {
         }
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    const fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
+    fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
         let mut secs = self.t.tv_sec.checked_add_unsigned(other.as_secs())?;
 
         // Nano calculations can't overflow because nanos are <1B which fit
         // in a u32.
-        let mut nsec = other.subsec_nanos() + self.t.tv_nsec as u32;
-        if nsec >= NSEC_PER_SEC as u32 {
-            nsec -= NSEC_PER_SEC as u32;
+        let mut nsec = other.subsec_nanos() + u32::try_from(self.t.tv_nsec).unwrap();
+        if nsec >= NSEC_PER_SEC.try_into().unwrap() {
+            nsec -= u32::try_from(NSEC_PER_SEC).unwrap();
             secs = secs.checked_add(1)?;
         }
         Some(Timespec { t: timespec { tv_sec: secs, tv_nsec: nsec as _ } })
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    const fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
+    fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
         let mut secs = self.t.tv_sec.checked_sub_unsigned(other.as_secs())?;
 
         // Similar to above, nanos can't overflow.
@@ -222,18 +220,15 @@ impl SystemTime {
         SystemTime(time)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
         self.0.sub_timespec(&other.0)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_add_duration(other)?))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_sub_duration(other)?))
     }
 }
diff --git a/library/std/src/sys/pal/mod.rs b/library/std/src/sys/pal/mod.rs
index 513121c6d30..dd5e83ee570 100644
--- a/library/std/src/sys/pal/mod.rs
+++ b/library/std/src/sys/pal/mod.rs
@@ -45,6 +45,10 @@ cfg_select! {
         mod trusty;
         pub use self::trusty::*;
     }
+    target_os = "vexos" => {
+        mod vexos;
+        pub use self::vexos::*;
+    }
     all(target_os = "wasi", target_env = "p2") => {
         mod wasip2;
         pub use self::wasip2::*;
diff --git a/library/std/src/sys/pal/sgx/abi/mod.rs b/library/std/src/sys/pal/sgx/abi/mod.rs
index 57247cffad3..b8c4d7740c4 100644
--- a/library/std/src/sys/pal/sgx/abi/mod.rs
+++ b/library/std/src/sys/pal/sgx/abi/mod.rs
@@ -67,7 +67,7 @@ extern "C" fn entry(p1: u64, p2: u64, p3: u64, secondary: bool, p4: u64, p5: u64
     let tls_guard = unsafe { tls.activate() };
 
     if secondary {
-        let join_notifier = super::thread::Thread::entry();
+        let join_notifier = crate::sys::thread::Thread::entry();
         drop(tls_guard);
         drop(join_notifier);
 
diff --git a/library/std/src/sys/pal/sgx/mod.rs b/library/std/src/sys/pal/sgx/mod.rs
index 4a297b6823f..9a33873af58 100644
--- a/library/std/src/sys/pal/sgx/mod.rs
+++ b/library/std/src/sys/pal/sgx/mod.rs
@@ -13,7 +13,6 @@ mod libunwind_integration;
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
-pub mod thread;
 pub mod thread_parking;
 pub mod time;
 pub mod waitqueue;
diff --git a/library/std/src/sys/pal/sgx/time.rs b/library/std/src/sys/pal/sgx/time.rs
index 603dae952ab..db4cf2804bf 100644
--- a/library/std/src/sys/pal/sgx/time.rs
+++ b/library/std/src/sys/pal/sgx/time.rs
@@ -32,22 +32,15 @@ impl SystemTime {
         SystemTime(usercalls::insecure_time())
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
-        // FIXME: ok_or_else with const closures
-        match self.0.checked_sub(other.0) {
-            Some(duration) => Ok(duration),
-            None => Err(other.0 - self.0),
-        }
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+        self.0.checked_sub(other.0).ok_or_else(|| other.0 - self.0)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_add(*other)?))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_sub(*other)?))
     }
 }
diff --git a/library/std/src/sys/pal/solid/mod.rs b/library/std/src/sys/pal/solid/mod.rs
index 0011cf256df..9ca6dc58118 100644
--- a/library/std/src/sys/pal/solid/mod.rs
+++ b/library/std/src/sys/pal/solid/mod.rs
@@ -10,10 +10,8 @@ pub mod itron {
     pub mod error;
     pub mod spin;
     pub mod task;
-    pub mod thread;
     pub mod thread_parking;
     pub mod time;
-    use super::unsupported;
 }
 
 // `error` is `pub(crate)` so that it can be accessed by `itron/error.rs` as
@@ -22,7 +20,7 @@ pub(crate) mod error;
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
-pub use self::itron::{thread, thread_parking};
+pub use self::itron::thread_parking;
 pub mod time;
 
 // SAFETY: must be called only once during runtime initialization.
diff --git a/library/std/src/sys/pal/solid/time.rs b/library/std/src/sys/pal/solid/time.rs
index e35e60df1a0..c39d715c6a6 100644
--- a/library/std/src/sys/pal/solid/time.rs
+++ b/library/std/src/sys/pal/solid/time.rs
@@ -39,8 +39,7 @@ impl SystemTime {
         Self(t)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
         if self.0 >= other.0 {
             Ok(Duration::from_secs((self.0 as u64).wrapping_sub(other.0 as u64)))
         } else {
@@ -48,13 +47,11 @@ impl SystemTime {
         }
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_add_unsigned(other.as_secs())?))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_sub_unsigned(other.as_secs())?))
     }
 }
diff --git a/library/std/src/sys/pal/teeos/mod.rs b/library/std/src/sys/pal/teeos/mod.rs
index c7b17777258..dd0155265da 100644
--- a/library/std/src/sys/pal/teeos/mod.rs
+++ b/library/std/src/sys/pal/teeos/mod.rs
@@ -9,7 +9,6 @@
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
-pub mod thread;
 #[allow(non_upper_case_globals)]
 #[path = "../unix/time.rs"]
 pub mod time;
diff --git a/library/std/src/sys/pal/trusty/mod.rs b/library/std/src/sys/pal/trusty/mod.rs
index 275f6062463..cf0c098f8a2 100644
--- a/library/std/src/sys/pal/trusty/mod.rs
+++ b/library/std/src/sys/pal/trusty/mod.rs
@@ -7,8 +7,6 @@ mod common;
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
-#[path = "../unsupported/thread.rs"]
-pub mod thread;
 #[path = "../unsupported/time.rs"]
 pub mod time;
 
diff --git a/library/std/src/sys/pal/uefi/helpers.rs b/library/std/src/sys/pal/uefi/helpers.rs
index b50574de937..c0d69c3e002 100644
--- a/library/std/src/sys/pal/uefi/helpers.rs
+++ b/library/std/src/sys/pal/uefi/helpers.rs
@@ -92,6 +92,9 @@ pub(crate) fn locate_handles(mut guid: Guid) -> io::Result<Vec<NonNull<crate::ff
 ///
 /// Queries a handle to determine if it supports a specified protocol. If the protocol is
 /// supported by the handle, it opens the protocol on behalf of the calling agent.
+///
+/// The protocol is opened with the attribute GET_PROTOCOL, which means the caller is not required
+/// to close the protocol interface with `EFI_BOOT_SERVICES.CloseProtocol()`
 pub(crate) fn open_protocol<T>(
     handle: NonNull<crate::ffi::c_void>,
     mut protocol_guid: Guid,
@@ -473,6 +476,7 @@ impl<'a> crate::fmt::Debug for DevicePathNode<'a> {
     }
 }
 
+/// Protocols installed by Rust side on a handle.
 pub(crate) struct OwnedProtocol<T> {
     guid: r_efi::efi::Guid,
     handle: NonNull<crate::ffi::c_void>,
diff --git a/library/std/src/sys/pal/uefi/mod.rs b/library/std/src/sys/pal/uefi/mod.rs
index 8911a2ee519..ebd311db1e1 100644
--- a/library/std/src/sys/pal/uefi/mod.rs
+++ b/library/std/src/sys/pal/uefi/mod.rs
@@ -17,7 +17,6 @@ pub mod helpers;
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
-pub mod thread;
 pub mod time;
 
 #[cfg(test)]
diff --git a/library/std/src/sys/pal/uefi/thread.rs b/library/std/src/sys/pal/uefi/thread.rs
deleted file mode 100644
index 47a48008c76..00000000000
--- a/library/std/src/sys/pal/uefi/thread.rs
+++ /dev/null
@@ -1,66 +0,0 @@
-use super::unsupported;
-use crate::ffi::CStr;
-use crate::io;
-use crate::num::NonZero;
-use crate::ptr::NonNull;
-use crate::time::{Duration, Instant};
-
-pub struct Thread(!);
-
-pub const DEFAULT_MIN_STACK_SIZE: usize = 64 * 1024;
-
-impl Thread {
-    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
-    pub unsafe fn new(
-        _stack: usize,
-        _name: Option<&str>,
-        _p: Box<dyn FnOnce()>,
-    ) -> io::Result<Thread> {
-        unsupported()
-    }
-
-    pub fn yield_now() {
-        // do nothing
-    }
-
-    pub fn set_name(_name: &CStr) {
-        // nope
-    }
-
-    pub fn sleep(dur: Duration) {
-        let boot_services: NonNull<r_efi::efi::BootServices> =
-            crate::os::uefi::env::boot_services().expect("can't sleep").cast();
-        let mut dur_ms = dur.as_micros();
-        // ceil up to the nearest microsecond
-        if dur.subsec_nanos() % 1000 > 0 {
-            dur_ms += 1;
-        }
-
-        while dur_ms > 0 {
-            let ms = crate::cmp::min(dur_ms, usize::MAX as u128);
-            let _ = unsafe { ((*boot_services.as_ptr()).stall)(ms as usize) };
-            dur_ms -= ms;
-        }
-    }
-
-    pub fn sleep_until(deadline: Instant) {
-        let now = Instant::now();
-
-        if let Some(delay) = deadline.checked_duration_since(now) {
-            Self::sleep(delay);
-        }
-    }
-
-    pub fn join(self) {
-        self.0
-    }
-}
-
-pub(crate) fn current_os_id() -> Option<u64> {
-    None
-}
-
-pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    // UEFI is single threaded
-    Ok(NonZero::new(1).unwrap())
-}
diff --git a/library/std/src/sys/pal/uefi/time.rs b/library/std/src/sys/pal/uefi/time.rs
index 36ce3f7ef96..c6636626fd5 100644
--- a/library/std/src/sys/pal/uefi/time.rs
+++ b/library/std/src/sys/pal/uefi/time.rs
@@ -80,32 +80,19 @@ impl SystemTime {
             .unwrap_or_else(|| panic!("time not implemented on this platform"))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
-        // FIXME: ok_or_else with const closures
-        match self.0.checked_sub(other.0) {
-            Some(duration) => Ok(duration),
-            None => Err(other.0 - self.0),
-        }
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+        self.0.checked_sub(other.0).ok_or_else(|| other.0 - self.0)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
-        let temp = self.0.checked_add(*other)?;
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+        let temp = Self(self.0.checked_add(*other)?);
 
         // Check if can be represented in UEFI
-        // FIXME: const PartialOrd
-        let mut cmp = temp.as_secs() - MAX_UEFI_TIME.0.as_secs();
-        if cmp == 0 {
-            cmp = temp.subsec_nanos() as u64 - MAX_UEFI_TIME.0.subsec_nanos() as u64;
-        }
-
-        if cmp <= 0 { Some(SystemTime(temp)) } else { None }
+        if temp <= MAX_UEFI_TIME { Some(temp) } else { None }
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
-        Some(SystemTime(self.0.checked_sub(*other)?))
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+        self.0.checked_sub(*other).map(Self)
     }
 }
 
diff --git a/library/std/src/sys/pal/unix/mod.rs b/library/std/src/sys/pal/unix/mod.rs
index ac5c823a1bf..dd1059fe04a 100644
--- a/library/std/src/sys/pal/unix/mod.rs
+++ b/library/std/src/sys/pal/unix/mod.rs
@@ -17,7 +17,6 @@ pub mod os;
 pub mod pipe;
 pub mod stack_overflow;
 pub mod sync;
-pub mod thread;
 pub mod thread_parking;
 pub mod time;
 
@@ -55,7 +54,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) {
     // thread-id for the main thread and so renaming the main thread will rename the
     // process and we only want to enable this on platforms we've tested.
     if cfg!(target_vendor = "apple") {
-        thread::Thread::set_name(&c"main");
+        crate::sys::thread::set_name(c"main");
     }
 
     unsafe fn sanitize_standard_fds() {
diff --git a/library/std/src/sys/pal/unix/os.rs b/library/std/src/sys/pal/unix/os.rs
index f0b6068e06c..7c9f3b7992f 100644
--- a/library/std/src/sys/pal/unix/os.rs
+++ b/library/std/src/sys/pal/unix/os.rs
@@ -16,7 +16,7 @@ use crate::{fmt, io, iter, mem, ptr, slice, str};
 
 const TMPBUF_SZ: usize = 128;
 
-const PATH_SEPARATOR: u8 = if cfg!(target_os = "redox") { b';' } else { b':' };
+const PATH_SEPARATOR: u8 = b':';
 
 unsafe extern "C" {
     #[cfg(not(any(target_os = "dragonfly", target_os = "vxworks", target_os = "rtems")))]
diff --git a/library/std/src/sys/pal/unix/stack_overflow.rs b/library/std/src/sys/pal/unix/stack_overflow.rs
index 0d2100d66bc..28b05d8a68a 100644
--- a/library/std/src/sys/pal/unix/stack_overflow.rs
+++ b/library/std/src/sys/pal/unix/stack_overflow.rs
@@ -72,7 +72,7 @@ mod imp {
     use crate::sync::OnceLock;
     use crate::sync::atomic::{Atomic, AtomicBool, AtomicPtr, AtomicUsize, Ordering};
     use crate::sys::pal::unix::os;
-    use crate::{io, mem, panic, ptr};
+    use crate::{io, mem, ptr};
 
     // Signal handler for the SIGSEGV and SIGBUS handlers. We've got guard pages
     // (unmapped pages) at the end of every thread's stack, so if a thread ends
@@ -148,6 +148,13 @@ mod imp {
 
         let mut guard_page_range = unsafe { install_main_guard() };
 
+        // Even for panic=immediate-abort, installing the guard pages is important for soundness.
+        // That said, we do not care about giving nice stackoverflow messages via our custom
+        // signal handler, just exit early and let the user enjoy the segfault.
+        if cfg!(panic = "immediate-abort") {
+            return;
+        }
+
         // SAFETY: assuming all platforms define struct sigaction as "zero-initializable"
         let mut action: sigaction = unsafe { mem::zeroed() };
         for &signal in &[SIGSEGV, SIGBUS] {
@@ -179,6 +186,9 @@ mod imp {
     /// Must be called only once
     #[forbid(unsafe_op_in_unsafe_fn)]
     pub unsafe fn cleanup() {
+        if cfg!(panic = "immediate-abort") {
+            return;
+        }
         // FIXME: I probably cause more bugs than I'm worth!
         // see https://github.com/rust-lang/rust/issues/111272
         unsafe { drop_handler(MAIN_ALTSTACK.load(Ordering::Relaxed)) };
@@ -230,7 +240,7 @@ mod imp {
     /// Mutates the alternate signal stack
     #[forbid(unsafe_op_in_unsafe_fn)]
     pub unsafe fn make_handler(main_thread: bool, thread_name: Option<Box<str>>) -> Handler {
-        if !NEED_ALTSTACK.load(Ordering::Acquire) {
+        if cfg!(panic = "immediate-abort") || !NEED_ALTSTACK.load(Ordering::Acquire) {
             return Handler::null();
         }
 
diff --git a/library/std/src/sys/pal/unix/time.rs b/library/std/src/sys/pal/unix/time.rs
index 328fe0bc960..c207f41cad4 100644
--- a/library/std/src/sys/pal/unix/time.rs
+++ b/library/std/src/sys/pal/unix/time.rs
@@ -38,18 +38,15 @@ impl SystemTime {
         SystemTime { t: Timespec::now(libc::CLOCK_REALTIME) }
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
         self.t.sub_timespec(&other.t)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime { t: self.t.checked_add_duration(other)? })
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime { t: self.t.checked_sub_duration(other)? })
     }
 }
@@ -136,36 +133,26 @@ impl Timespec {
         Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap()
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
-        // FIXME: const PartialOrd
-        let mut cmp = self.tv_sec - other.tv_sec;
-        if cmp == 0 {
-            cmp = self.tv_nsec.as_inner() as i64 - other.tv_nsec.as_inner() as i64;
+    pub fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
+        // When a >= b, the difference fits in u64.
+        fn sub_ge_to_unsigned(a: i64, b: i64) -> u64 {
+            debug_assert!(a >= b);
+            a.wrapping_sub(b).cast_unsigned()
         }
 
-        if cmp >= 0 {
-            // NOTE(eddyb) two aspects of this `if`-`else` are required for LLVM
-            // to optimize it into a branchless form (see also #75545):
-            //
-            // 1. `self.tv_sec - other.tv_sec` shows up as a common expression
-            //    in both branches, i.e. the `else` must have its `- 1`
-            //    subtraction after the common one, not interleaved with it
-            //    (it used to be `self.tv_sec - 1 - other.tv_sec`)
-            //
-            // 2. the `Duration::new` call (or any other additional complexity)
-            //    is outside of the `if`-`else`, not duplicated in both branches
-            //
-            // Ideally this code could be rearranged such that it more
-            // directly expresses the lower-cost behavior we want from it.
+        if self >= other {
             let (secs, nsec) = if self.tv_nsec.as_inner() >= other.tv_nsec.as_inner() {
                 (
-                    (self.tv_sec - other.tv_sec) as u64,
+                    sub_ge_to_unsigned(self.tv_sec, other.tv_sec),
                     self.tv_nsec.as_inner() - other.tv_nsec.as_inner(),
                 )
             } else {
+                // Following sequence of assertions explain why `self.tv_sec - 1` does not underflow.
+                debug_assert!(self.tv_nsec < other.tv_nsec);
+                debug_assert!(self.tv_sec > other.tv_sec);
+                debug_assert!(self.tv_sec > i64::MIN);
                 (
-                    (self.tv_sec - other.tv_sec - 1) as u64,
+                    sub_ge_to_unsigned(self.tv_sec - 1, other.tv_sec),
                     self.tv_nsec.as_inner() + (NSEC_PER_SEC as u32) - other.tv_nsec.as_inner(),
                 )
             };
@@ -179,8 +166,7 @@ impl Timespec {
         }
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
         let mut secs = self.tv_sec.checked_add_unsigned(other.as_secs())?;
 
         // Nano calculations can't overflow because nanos are <1B which fit
@@ -190,11 +176,10 @@ impl Timespec {
             nsec -= NSEC_PER_SEC as u32;
             secs = secs.checked_add(1)?;
         }
-        Some(unsafe { Timespec::new_unchecked(secs, nsec as i64) })
+        Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
         let mut secs = self.tv_sec.checked_sub_unsigned(other.as_secs())?;
 
         // Similar to above, nanos can't overflow.
@@ -203,7 +188,7 @@ impl Timespec {
             nsec += NSEC_PER_SEC as i32;
             secs = secs.checked_sub(1)?;
         }
-        Some(unsafe { Timespec::new_unchecked(secs, nsec as i64) })
+        Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
     }
 
     #[allow(dead_code)]
diff --git a/library/std/src/sys/pal/unix/weak.rs b/library/std/src/sys/pal/unix/weak.rs
index c8cf75b876c..a3b980a3f3d 100644
--- a/library/std/src/sys/pal/unix/weak.rs
+++ b/library/std/src/sys/pal/unix/weak.rs
@@ -22,11 +22,24 @@
 #![allow(dead_code, unused_macros)]
 #![forbid(unsafe_op_in_unsafe_fn)]
 
-use crate::ffi::CStr;
-use crate::marker::PhantomData;
-use crate::sync::atomic::{self, Atomic, AtomicPtr, Ordering};
+use crate::ffi::{CStr, c_char, c_void};
+use crate::marker::{FnPtr, PhantomData};
+use crate::sync::atomic::{Atomic, AtomicPtr, Ordering};
 use crate::{mem, ptr};
 
+// We currently only test `dlsym!`, but that doesn't work on all platforms, so
+// we gate the tests to only the platforms where it is actually used.
+//
+// FIXME(joboet): add more tests, reorganise the whole module and get rid of
+//                `#[allow(dead_code, unused_macros)]`.
+#[cfg(any(
+    target_vendor = "apple",
+    all(target_os = "linux", target_env = "gnu"),
+    target_os = "freebsd",
+))]
+#[cfg(test)]
+mod tests;
+
 // We can use true weak linkage on ELF targets.
 #[cfg(all(unix, not(target_vendor = "apple")))]
 pub(crate) macro weak {
@@ -64,7 +77,7 @@ impl<F: Copy> ExternWeak<F> {
 
 pub(crate) macro dlsym {
     (fn $name:ident($($param:ident : $t:ty),* $(,)?) -> $ret:ty;) => (
-         dlsym!(
+        dlsym!(
             #[link_name = stringify!($name)]
             fn $name($($param : $t),*) -> $ret;
         );
@@ -73,21 +86,39 @@ pub(crate) macro dlsym {
         #[link_name = $sym:expr]
         fn $name:ident($($param:ident : $t:ty),* $(,)?) -> $ret:ty;
     ) => (
-        static DLSYM: DlsymWeak<unsafe extern "C" fn($($t),*) -> $ret> =
-            DlsymWeak::new(concat!($sym, '\0'));
+        static DLSYM: DlsymWeak<unsafe extern "C" fn($($t),*) -> $ret> = {
+            let Ok(name) = CStr::from_bytes_with_nul(concat!($sym, '\0').as_bytes()) else {
+                panic!("symbol name may not contain NUL")
+            };
+
+            // SAFETY: Whoever calls the function pointer returned by `get()`
+            // is responsible for ensuring that the signature is correct. Just
+            // like with extern blocks, this is syntactically enforced by making
+            // the function pointer be unsafe.
+            unsafe { DlsymWeak::new(name) }
+        };
+
         let $name = &DLSYM;
     )
 }
+
 pub(crate) struct DlsymWeak<F> {
-    name: &'static str,
+    /// A pointer to the nul-terminated name of the symbol.
+    // Use a pointer instead of `&'static CStr` to save space.
+    name: *const c_char,
     func: Atomic<*mut libc::c_void>,
     _marker: PhantomData<F>,
 }
 
-impl<F> DlsymWeak<F> {
-    pub(crate) const fn new(name: &'static str) -> Self {
+impl<F: FnPtr> DlsymWeak<F> {
+    /// # Safety
+    ///
+    /// If the signature of `F` does not match the signature of the symbol (if
+    /// it exists), calling the function pointer returned by `get()` is
+    /// undefined behaviour.
+    pub(crate) const unsafe fn new(name: &'static CStr) -> Self {
         DlsymWeak {
-            name,
+            name: name.as_ptr(),
             func: AtomicPtr::new(ptr::without_provenance_mut(1)),
             _marker: PhantomData,
         }
@@ -95,62 +126,59 @@ impl<F> DlsymWeak<F> {
 
     #[inline]
     pub(crate) fn get(&self) -> Option<F> {
-        unsafe {
-            // Relaxed is fine here because we fence before reading through the
-            // pointer (see the comment below).
-            match self.func.load(Ordering::Relaxed) {
-                func if func.addr() == 1 => self.initialize(),
-                func if func.is_null() => None,
-                func => {
-                    let func = mem::transmute_copy::<*mut libc::c_void, F>(&func);
-                    // The caller is presumably going to read through this value
-                    // (by calling the function we've dlsymed). This means we'd
-                    // need to have loaded it with at least C11's consume
-                    // ordering in order to be guaranteed that the data we read
-                    // from the pointer isn't from before the pointer was
-                    // stored. Rust has no equivalent to memory_order_consume,
-                    // so we use an acquire fence (sorry, ARM).
-                    //
-                    // Now, in practice this likely isn't needed even on CPUs
-                    // where relaxed and consume mean different things. The
-                    // symbols we're loading are probably present (or not) at
-                    // init, and even if they aren't the runtime dynamic loader
-                    // is extremely likely have sufficient barriers internally
-                    // (possibly implicitly, for example the ones provided by
-                    // invoking `mprotect`).
-                    //
-                    // That said, none of that's *guaranteed*, and so we fence.
-                    atomic::fence(Ordering::Acquire);
-                    Some(func)
-                }
-            }
+        // The caller is presumably going to read through this value
+        // (by calling the function we've dlsymed). This means we'd
+        // need to have loaded it with at least C11's consume
+        // ordering in order to be guaranteed that the data we read
+        // from the pointer isn't from before the pointer was
+        // stored. Rust has no equivalent to memory_order_consume,
+        // so we use an acquire load (sorry, ARM).
+        //
+        // Now, in practice this likely isn't needed even on CPUs
+        // where relaxed and consume mean different things. The
+        // symbols we're loading are probably present (or not) at
+        // init, and even if they aren't the runtime dynamic loader
+        // is extremely likely have sufficient barriers internally
+        // (possibly implicitly, for example the ones provided by
+        // invoking `mprotect`).
+        //
+        // That said, none of that's *guaranteed*, so we use acquire.
+        match self.func.load(Ordering::Acquire) {
+            func if func.addr() == 1 => self.initialize(),
+            func if func.is_null() => None,
+            // SAFETY:
+            // `func` is not null and `F` implements `FnPtr`, thus this
+            // transmutation is well-defined. It is the responsibility of the
+            // creator of this `DlsymWeak` to ensure that calling the resulting
+            // function pointer does not result in undefined behaviour (though
+            // the `dlsym!` macro delegates this responsibility to the caller
+            // of the function by using `unsafe` function pointers).
+            // FIXME: use `transmute` once it stops complaining about generics.
+            func => Some(unsafe { mem::transmute_copy::<*mut c_void, F>(&func) }),
         }
     }
 
     // Cold because it should only happen during first-time initialization.
     #[cold]
-    unsafe fn initialize(&self) -> Option<F> {
-        assert_eq!(size_of::<F>(), size_of::<*mut libc::c_void>());
-
-        let val = unsafe { fetch(self.name) };
-        // This synchronizes with the acquire fence in `get`.
+    fn initialize(&self) -> Option<F> {
+        // SAFETY: `self.name` was created from a `&'static CStr` and is
+        // therefore a valid C string pointer.
+        let val = unsafe { libc::dlsym(libc::RTLD_DEFAULT, self.name) };
+        // This synchronizes with the acquire load in `get`.
         self.func.store(val, Ordering::Release);
 
         if val.is_null() {
             None
         } else {
+            // SAFETY: see the comment in `get`.
+            // FIXME: use `transmute` once it stops complaining about generics.
             Some(unsafe { mem::transmute_copy::<*mut libc::c_void, F>(&val) })
         }
     }
 }
 
-unsafe fn fetch(name: &str) -> *mut libc::c_void {
-    let name = match CStr::from_bytes_with_nul(name.as_bytes()) {
-        Ok(cstr) => cstr,
-        Err(..) => return ptr::null_mut(),
-    };
-    unsafe { libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr()) }
-}
+unsafe impl<F> Send for DlsymWeak<F> {}
+unsafe impl<F> Sync for DlsymWeak<F> {}
 
 #[cfg(not(any(target_os = "linux", target_os = "android")))]
 pub(crate) macro syscall {
diff --git a/library/std/src/sys/pal/unix/weak/tests.rs b/library/std/src/sys/pal/unix/weak/tests.rs
new file mode 100644
index 00000000000..d807ba64e35
--- /dev/null
+++ b/library/std/src/sys/pal/unix/weak/tests.rs
@@ -0,0 +1,32 @@
+use super::*;
+
+#[test]
+fn dlsym_existing() {
+    const TEST_STRING: &'static CStr = c"Ferris!";
+
+    // Try to find a symbol that definitely exists.
+    dlsym! {
+        fn strlen(cs: *const c_char) -> usize;
+    }
+
+    dlsym! {
+        #[link_name = "strlen"]
+        fn custom_name(cs: *const c_char) -> usize;
+    }
+
+    let strlen = strlen.get().unwrap();
+    assert_eq!(unsafe { strlen(TEST_STRING.as_ptr()) }, TEST_STRING.count_bytes());
+
+    let custom_name = custom_name.get().unwrap();
+    assert_eq!(unsafe { custom_name(TEST_STRING.as_ptr()) }, TEST_STRING.count_bytes());
+}
+
+#[test]
+fn dlsym_missing() {
+    // Try to find a symbol that definitely does not exist.
+    dlsym! {
+        fn test_symbol_that_does_not_exist() -> i32;
+    }
+
+    assert!(test_symbol_that_does_not_exist.get().is_none());
+}
diff --git a/library/std/src/sys/pal/unsupported/mod.rs b/library/std/src/sys/pal/unsupported/mod.rs
index 5e3295b1331..e64bbc7c616 100644
--- a/library/std/src/sys/pal/unsupported/mod.rs
+++ b/library/std/src/sys/pal/unsupported/mod.rs
@@ -2,7 +2,6 @@
 
 pub mod os;
 pub mod pipe;
-pub mod thread;
 pub mod time;
 
 mod common;
diff --git a/library/std/src/sys/pal/unsupported/time.rs b/library/std/src/sys/pal/unsupported/time.rs
index 0c387917044..6d67b538a96 100644
--- a/library/std/src/sys/pal/unsupported/time.rs
+++ b/library/std/src/sys/pal/unsupported/time.rs
@@ -31,22 +31,15 @@ impl SystemTime {
         panic!("time not implemented on this platform")
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
-        // FIXME: ok_or_else with const closures
-        match self.0.checked_sub(other.0) {
-            Some(duration) => Ok(duration),
-            None => Err(other.0 - self.0),
-        }
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+        self.0.checked_sub(other.0).ok_or_else(|| other.0 - self.0)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_add(*other)?))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_sub(*other)?))
     }
 }
diff --git a/library/std/src/sys/pal/vexos/mod.rs b/library/std/src/sys/pal/vexos/mod.rs
new file mode 100644
index 00000000000..61a34b0f68a
--- /dev/null
+++ b/library/std/src/sys/pal/vexos/mod.rs
@@ -0,0 +1,80 @@
+#[path = "../unsupported/os.rs"]
+pub mod os;
+#[path = "../unsupported/pipe.rs"]
+pub mod pipe;
+pub mod time;
+
+#[expect(dead_code)]
+#[path = "../unsupported/common.rs"]
+mod unsupported_common;
+
+pub use unsupported_common::{
+    decode_error_kind, init, is_interrupted, unsupported, unsupported_err,
+};
+
+use crate::arch::global_asm;
+use crate::ptr;
+use crate::sys::stdio;
+use crate::time::{Duration, Instant};
+
+global_asm!(
+    r#"
+    .section .boot, "ax"
+    .global _boot
+
+    _boot:
+        ldr sp, =__stack_top @ Set up the user stack.
+        b _start             @ Jump to the Rust entrypoint.
+    "#
+);
+
+#[cfg(not(test))]
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn _start() -> ! {
+    unsafe extern "C" {
+        static mut __bss_start: u8;
+        static mut __bss_end: u8;
+
+        fn main() -> i32;
+    }
+
+    // Clear the .bss (uninitialized statics) section by filling it with zeroes.
+    // This is required, since the compiler assumes it will be zeroed on first access.
+    ptr::write_bytes(
+        &raw mut __bss_start,
+        0,
+        (&raw mut __bss_end).offset_from_unsigned(&raw mut __bss_start),
+    );
+
+    main();
+
+    cleanup();
+    abort_internal()
+}
+
+// SAFETY: must be called only once during runtime cleanup.
+// NOTE: this is not guaranteed to run, for example when the program aborts.
+pub unsafe fn cleanup() {
+    let exit_time = Instant::now();
+    const FLUSH_TIMEOUT: Duration = Duration::from_millis(15);
+
+    // Force the serial buffer to flush
+    while exit_time.elapsed() < FLUSH_TIMEOUT {
+        vex_sdk::vexTasksRun();
+
+        // If the buffer has been fully flushed, exit the loop
+        if vex_sdk::vexSerialWriteFree(stdio::STDIO_CHANNEL) == (stdio::STDOUT_BUF_SIZE as i32) {
+            break;
+        }
+    }
+}
+
+pub fn abort_internal() -> ! {
+    unsafe {
+        vex_sdk::vexSystemExitRequest();
+
+        loop {
+            vex_sdk::vexTasksRun();
+        }
+    }
+}
diff --git a/library/std/src/sys/pal/vexos/time.rs b/library/std/src/sys/pal/vexos/time.rs
new file mode 100644
index 00000000000..f95d96cd27a
--- /dev/null
+++ b/library/std/src/sys/pal/vexos/time.rs
@@ -0,0 +1,28 @@
+use crate::time::Duration;
+
+#[expect(dead_code)]
+#[path = "../unsupported/time.rs"]
+mod unsupported_time;
+pub use unsupported_time::{SystemTime, UNIX_EPOCH};
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
+pub struct Instant(Duration);
+
+impl Instant {
+    pub fn now() -> Instant {
+        let micros = unsafe { vex_sdk::vexSystemHighResTimeGet() };
+        Self(Duration::from_micros(micros))
+    }
+
+    pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
+        self.0.checked_sub(other.0)
+    }
+
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
+        Some(Instant(self.0.checked_add(*other)?))
+    }
+
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
+        Some(Instant(self.0.checked_sub(*other)?))
+    }
+}
diff --git a/library/std/src/sys/pal/wasip1/mod.rs b/library/std/src/sys/pal/wasip1/mod.rs
index 61dd1c3f98b..ae5da3c1f77 100644
--- a/library/std/src/sys/pal/wasip1/mod.rs
+++ b/library/std/src/sys/pal/wasip1/mod.rs
@@ -20,7 +20,6 @@ pub mod futex;
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
-pub mod thread;
 pub mod time;
 
 #[path = "../unsupported/common.rs"]
diff --git a/library/std/src/sys/pal/wasip1/thread.rs b/library/std/src/sys/pal/wasip1/thread.rs
deleted file mode 100644
index e062b49bd7a..00000000000
--- a/library/std/src/sys/pal/wasip1/thread.rs
+++ /dev/null
@@ -1,214 +0,0 @@
-#![forbid(unsafe_op_in_unsafe_fn)]
-
-use crate::ffi::CStr;
-use crate::num::NonZero;
-use crate::time::{Duration, Instant};
-use crate::{io, mem};
-
-cfg_select! {
-    target_feature = "atomics" => {
-        use crate::cmp;
-        use crate::ptr;
-        use crate::sys::os;
-        // Add a few symbols not in upstream `libc` just yet.
-        mod libc {
-            pub use crate::ffi;
-            pub use libc::*;
-
-            // defined in wasi-libc
-            // https://github.com/WebAssembly/wasi-libc/blob/a6f871343313220b76009827ed0153586361c0d5/libc-top-half/musl/include/alltypes.h.in#L108
-            #[repr(C)]
-            union pthread_attr_union {
-                __i: [ffi::c_int; if size_of::<ffi::c_long>() == 8 { 14 } else { 9 }],
-                __vi: [ffi::c_int; if size_of::<ffi::c_long>() == 8 { 14 } else { 9 }],
-                __s: [ffi::c_ulong; if size_of::<ffi::c_long>() == 8 { 7 } else { 9 }],
-            }
-
-            #[repr(C)]
-            pub struct pthread_attr_t {
-                __u: pthread_attr_union,
-            }
-
-            #[allow(non_camel_case_types)]
-            pub type pthread_t = *mut ffi::c_void;
-
-            pub const _SC_NPROCESSORS_ONLN: ffi::c_int = 84;
-
-            unsafe extern "C" {
-                pub fn pthread_create(
-                    native: *mut pthread_t,
-                    attr: *const pthread_attr_t,
-                    f: extern "C" fn(*mut ffi::c_void) -> *mut ffi::c_void,
-                    value: *mut ffi::c_void,
-                ) -> ffi::c_int;
-                pub fn pthread_join(native: pthread_t, value: *mut *mut ffi::c_void) -> ffi::c_int;
-                pub fn pthread_attr_init(attrp: *mut pthread_attr_t) -> ffi::c_int;
-                pub fn pthread_attr_setstacksize(
-                    attr: *mut pthread_attr_t,
-                    stack_size: libc::size_t,
-                ) -> ffi::c_int;
-                pub fn pthread_attr_destroy(attr: *mut pthread_attr_t) -> ffi::c_int;
-                pub fn pthread_detach(thread: pthread_t) -> ffi::c_int;
-            }
-        }
-
-        pub struct Thread {
-            id: libc::pthread_t,
-        }
-
-        impl Drop for Thread {
-            fn drop(&mut self) {
-                let ret = unsafe { libc::pthread_detach(self.id) };
-                debug_assert_eq!(ret, 0);
-            }
-        }
-    }
-    _ => {
-        pub struct Thread(!);
-    }
-}
-
-pub const DEFAULT_MIN_STACK_SIZE: usize = 1024 * 1024;
-
-impl Thread {
-    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
-    cfg_select! {
-        target_feature = "atomics" => {
-            pub unsafe fn new(stack: usize, _name: Option<&str>, p: Box<dyn FnOnce()>) -> io::Result<Thread> {
-                let p = Box::into_raw(Box::new(p));
-                let mut native: libc::pthread_t = unsafe { mem::zeroed() };
-                let mut attr: libc::pthread_attr_t = unsafe { mem::zeroed() };
-                assert_eq!(unsafe { libc::pthread_attr_init(&mut attr) }, 0);
-
-                let stack_size = cmp::max(stack, DEFAULT_MIN_STACK_SIZE);
-
-                match unsafe { libc::pthread_attr_setstacksize(&mut attr, stack_size) } {
-                    0 => {}
-                    n => {
-                        assert_eq!(n, libc::EINVAL);
-                        // EINVAL means |stack_size| is either too small or not a
-                        // multiple of the system page size. Because it's definitely
-                        // >= PTHREAD_STACK_MIN, it must be an alignment issue.
-                        // Round up to the nearest page and try again.
-                        let page_size = os::page_size();
-                        let stack_size =
-                            (stack_size + page_size - 1) & (-(page_size as isize - 1) as usize - 1);
-                        assert_eq!(unsafe { libc::pthread_attr_setstacksize(&mut attr, stack_size) }, 0);
-                    }
-                };
-
-                let ret = unsafe { libc::pthread_create(&mut native, &attr, thread_start, p as *mut _) };
-                // Note: if the thread creation fails and this assert fails, then p will
-                // be leaked. However, an alternative design could cause double-free
-                // which is clearly worse.
-                assert_eq!(unsafe {libc::pthread_attr_destroy(&mut attr) }, 0);
-
-                return if ret != 0 {
-                    // The thread failed to start and as a result p was not consumed. Therefore, it is
-                    // safe to reconstruct the box so that it gets deallocated.
-                    unsafe { drop(Box::from_raw(p)); }
-                    Err(io::Error::from_raw_os_error(ret))
-                } else {
-                    Ok(Thread { id: native })
-                };
-
-                extern "C" fn thread_start(main: *mut libc::c_void) -> *mut libc::c_void {
-                    unsafe {
-                        // Finally, let's run some code.
-                        Box::from_raw(main as *mut Box<dyn FnOnce()>)();
-                    }
-                    ptr::null_mut()
-                }
-            }
-        }
-        _ => {
-            pub unsafe fn new(_stack: usize, _name: Option<&str>, _p: Box<dyn FnOnce()>) -> io::Result<Thread> {
-                crate::sys::unsupported()
-            }
-        }
-    }
-
-    pub fn yield_now() {
-        let ret = unsafe { wasi::sched_yield() };
-        debug_assert_eq!(ret, Ok(()));
-    }
-
-    pub fn set_name(_name: &CStr) {
-        // nope
-    }
-
-    pub fn sleep(dur: Duration) {
-        let mut nanos = dur.as_nanos();
-        while nanos > 0 {
-            const USERDATA: wasi::Userdata = 0x0123_45678;
-
-            let clock = wasi::SubscriptionClock {
-                id: wasi::CLOCKID_MONOTONIC,
-                timeout: u64::try_from(nanos).unwrap_or(u64::MAX),
-                precision: 0,
-                flags: 0,
-            };
-            nanos -= u128::from(clock.timeout);
-
-            let in_ = wasi::Subscription {
-                userdata: USERDATA,
-                u: wasi::SubscriptionU { tag: 0, u: wasi::SubscriptionUU { clock } },
-            };
-            unsafe {
-                let mut event: wasi::Event = mem::zeroed();
-                let res = wasi::poll_oneoff(&in_, &mut event, 1);
-                match (res, event) {
-                    (
-                        Ok(1),
-                        wasi::Event {
-                            userdata: USERDATA,
-                            error: wasi::ERRNO_SUCCESS,
-                            type_: wasi::EVENTTYPE_CLOCK,
-                            ..
-                        },
-                    ) => {}
-                    _ => panic!("thread::sleep(): unexpected result of poll_oneoff"),
-                }
-            }
-        }
-    }
-
-    pub fn sleep_until(deadline: Instant) {
-        let now = Instant::now();
-
-        if let Some(delay) = deadline.checked_duration_since(now) {
-            Self::sleep(delay);
-        }
-    }
-
-    pub fn join(self) {
-        cfg_select! {
-            target_feature = "atomics" => {
-                let id = mem::ManuallyDrop::new(self).id;
-                let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
-                if ret != 0 {
-                    rtabort!("failed to join thread: {}", io::Error::from_raw_os_error(ret));
-                }
-            }
-            _ => {
-                self.0
-            }
-        }
-    }
-}
-
-pub(crate) fn current_os_id() -> Option<u64> {
-    None
-}
-
-pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    cfg_select! {
-        target_feature = "atomics" => {
-            match unsafe { libc::sysconf(libc::_SC_NPROCESSORS_ONLN) } {
-                -1 => Err(io::Error::last_os_error()),
-                cpus => NonZero::new(cpus as usize).ok_or(io::Error::UNKNOWN_THREAD_COUNT),
-            }
-        }
-        _ => crate::sys::unsupported(),
-    }
-}
diff --git a/library/std/src/sys/pal/wasip1/time.rs b/library/std/src/sys/pal/wasip1/time.rs
index 892661b312b..0d8d0b59ac1 100644
--- a/library/std/src/sys/pal/wasip1/time.rs
+++ b/library/std/src/sys/pal/wasip1/time.rs
@@ -43,34 +43,23 @@ impl SystemTime {
         SystemTime(current_time(wasi::CLOCKID_REALTIME))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn from_wasi_timestamp(ts: wasi::Timestamp) -> SystemTime {
+    pub fn from_wasi_timestamp(ts: wasi::Timestamp) -> SystemTime {
         SystemTime(Duration::from_nanos(ts))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn to_wasi_timestamp(&self) -> Option<wasi::Timestamp> {
-        // FIXME: const TryInto
-        let ns = self.0.as_nanos();
-        if ns <= u64::MAX as u128 { Some(ns as u64) } else { None }
+    pub fn to_wasi_timestamp(&self) -> Option<wasi::Timestamp> {
+        self.0.as_nanos().try_into().ok()
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
-        // FIXME: ok_or_else with const closures
-        match self.0.checked_sub(other.0) {
-            Some(duration) => Ok(duration),
-            None => Err(other.0 - self.0),
-        }
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+        self.0.checked_sub(other.0).ok_or_else(|| other.0 - self.0)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_add(*other)?))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_sub(*other)?))
     }
 }
diff --git a/library/std/src/sys/pal/wasip2/mod.rs b/library/std/src/sys/pal/wasip2/mod.rs
index 5f3fb6d6ddf..c1d89da2677 100644
--- a/library/std/src/sys/pal/wasip2/mod.rs
+++ b/library/std/src/sys/pal/wasip2/mod.rs
@@ -14,7 +14,6 @@ pub mod futex;
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
-pub mod thread;
 pub mod time;
 
 #[path = "../unsupported/common.rs"]
diff --git a/library/std/src/sys/pal/wasip2/thread.rs b/library/std/src/sys/pal/wasip2/thread.rs
deleted file mode 100644
index ad52918f15a..00000000000
--- a/library/std/src/sys/pal/wasip2/thread.rs
+++ /dev/null
@@ -1,73 +0,0 @@
-use crate::ffi::CStr;
-use crate::io;
-use crate::num::NonZero;
-use crate::time::{Duration, Instant};
-
-pub struct Thread(!);
-
-pub const DEFAULT_MIN_STACK_SIZE: usize = 1024 * 1024;
-
-impl Thread {
-    pub unsafe fn new(
-        _stack: usize,
-        _name: Option<&str>,
-        _p: Box<dyn FnOnce()>,
-    ) -> io::Result<Thread> {
-        // Note that unlike WASIp1 even if the wasm `atomics` feature is enabled
-        // there is no support for threads, not even experimentally, not even in
-        // wasi-libc. Thus this is unconditionally unsupported.
-        crate::sys::unsupported()
-    }
-
-    pub fn yield_now() {
-        // no API for this in WASIp2, but there's also no threads, so that's
-        // sort of expected.
-    }
-
-    pub fn set_name(_name: &CStr) {
-        // nope
-    }
-
-    pub fn sleep(dur: Duration) {
-        // Sleep in increments of `u64::MAX` nanoseconds until the `dur` is
-        // entirely drained.
-        let mut remaining = dur.as_nanos();
-        while remaining > 0 {
-            let amt = u64::try_from(remaining).unwrap_or(u64::MAX);
-            wasip2::clocks::monotonic_clock::subscribe_duration(amt).block();
-            remaining -= u128::from(amt);
-        }
-    }
-
-    pub fn sleep_until(deadline: Instant) {
-        match u64::try_from(deadline.into_inner().as_duration().as_nanos()) {
-            // If the point in time we're sleeping to fits within a 64-bit
-            // number of nanoseconds then directly use `subscribe_instant`.
-            Ok(deadline) => {
-                wasip2::clocks::monotonic_clock::subscribe_instant(deadline).block();
-            }
-            // ... otherwise we're sleeping for 500+ years relative to the
-            // "start" of what the system is using as a clock so speed/accuracy
-            // is not so much of a concern. Use `sleep` instead.
-            Err(_) => {
-                let now = Instant::now();
-
-                if let Some(delay) = deadline.checked_duration_since(now) {
-                    Self::sleep(delay);
-                }
-            }
-        }
-    }
-
-    pub fn join(self) {
-        self.0
-    }
-}
-
-pub(crate) fn current_os_id() -> Option<u64> {
-    None
-}
-
-pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    crate::sys::unsupported()
-}
diff --git a/library/std/src/sys/pal/wasip2/time.rs b/library/std/src/sys/pal/wasip2/time.rs
index f1f6839774b..43489183994 100644
--- a/library/std/src/sys/pal/wasip2/time.rs
+++ b/library/std/src/sys/pal/wasip2/time.rs
@@ -25,7 +25,7 @@ impl Instant {
         Some(Instant(self.0.checked_sub(*other)?))
     }
 
-    pub(super) fn as_duration(&self) -> &Duration {
+    pub(crate) fn as_duration(&self) -> &Duration {
         &self.0
     }
 }
@@ -36,34 +36,23 @@ impl SystemTime {
         SystemTime(Duration::new(now.seconds, now.nanoseconds))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn from_wasi_timestamp(ts: wasi::Timestamp) -> SystemTime {
+    pub fn from_wasi_timestamp(ts: wasi::Timestamp) -> SystemTime {
         SystemTime(Duration::from_nanos(ts))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn to_wasi_timestamp(&self) -> Option<wasi::Timestamp> {
-        // FIXME: const TryInto
-        let ns = self.0.as_nanos();
-        if ns <= u64::MAX as u128 { Some(ns as u64) } else { None }
+    pub fn to_wasi_timestamp(&self) -> Option<wasi::Timestamp> {
+        self.0.as_nanos().try_into().ok()
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
-        // FIXME: ok_or_else with const closures
-        match self.0.checked_sub(other.0) {
-            Some(duration) => Ok(duration),
-            None => Err(other.0 - self.0),
-        }
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+        self.0.checked_sub(other.0).ok_or_else(|| other.0 - self.0)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_add(*other)?))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_sub(*other)?))
     }
 }
diff --git a/library/std/src/sys/pal/wasm/atomics/thread.rs b/library/std/src/sys/pal/wasm/atomics/thread.rs
deleted file mode 100644
index 42a7dbdf8b8..00000000000
--- a/library/std/src/sys/pal/wasm/atomics/thread.rs
+++ /dev/null
@@ -1,75 +0,0 @@
-use crate::ffi::CStr;
-use crate::io;
-use crate::num::NonZero;
-use crate::sys::unsupported;
-use crate::time::{Duration, Instant};
-
-pub struct Thread(!);
-
-pub const DEFAULT_MIN_STACK_SIZE: usize = 1024 * 1024;
-
-impl Thread {
-    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
-    pub unsafe fn new(
-        _stack: usize,
-        _name: Option<&str>,
-        _p: Box<dyn FnOnce()>,
-    ) -> io::Result<Thread> {
-        unsupported()
-    }
-
-    pub fn yield_now() {}
-
-    pub fn set_name(_name: &CStr) {}
-
-    pub fn sleep(dur: Duration) {
-        #[cfg(target_arch = "wasm32")]
-        use core::arch::wasm32 as wasm;
-        #[cfg(target_arch = "wasm64")]
-        use core::arch::wasm64 as wasm;
-
-        use crate::cmp;
-
-        // Use an atomic wait to block the current thread artificially with a
-        // timeout listed. Note that we should never be notified (return value
-        // of 0) or our comparison should never fail (return value of 1) so we
-        // should always only resume execution through a timeout (return value
-        // 2).
-        let mut nanos = dur.as_nanos();
-        while nanos > 0 {
-            let amt = cmp::min(i64::MAX as u128, nanos);
-            let mut x = 0;
-            let val = unsafe { wasm::memory_atomic_wait32(&mut x, 0, amt as i64) };
-            debug_assert_eq!(val, 2);
-            nanos -= amt;
-        }
-    }
-
-    pub fn sleep_until(deadline: Instant) {
-        let now = Instant::now();
-
-        if let Some(delay) = deadline.checked_duration_since(now) {
-            Self::sleep(delay);
-        }
-    }
-
-    pub fn join(self) {}
-}
-
-pub(crate) fn current_os_id() -> Option<u64> {
-    None
-}
-
-pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    unsupported()
-}
-
-pub mod guard {
-    pub type Guard = !;
-    pub unsafe fn current() -> Option<Guard> {
-        None
-    }
-    pub unsafe fn init() -> Option<Guard> {
-        None
-    }
-}
diff --git a/library/std/src/sys/pal/wasm/mod.rs b/library/std/src/sys/pal/wasm/mod.rs
index 346c9ff88c9..a20cd0e9ac7 100644
--- a/library/std/src/sys/pal/wasm/mod.rs
+++ b/library/std/src/sys/pal/wasm/mod.rs
@@ -23,18 +23,9 @@ pub mod pipe;
 #[path = "../unsupported/time.rs"]
 pub mod time;
 
-cfg_select! {
-    target_feature = "atomics" => {
-        #[path = "atomics/futex.rs"]
-        pub mod futex;
-        #[path = "atomics/thread.rs"]
-        pub mod thread;
-    }
-    _ => {
-        #[path = "../unsupported/thread.rs"]
-        pub mod thread;
-    }
-}
+#[cfg(target_feature = "atomics")]
+#[path = "atomics/futex.rs"]
+pub mod futex;
 
 #[path = "../unsupported/common.rs"]
 #[deny(unsafe_op_in_unsafe_fn)]
diff --git a/library/std/src/sys/pal/windows/c/bindings.txt b/library/std/src/sys/pal/windows/c/bindings.txt
index abc1c19827f..9009aa09f48 100644
--- a/library/std/src/sys/pal/windows/c/bindings.txt
+++ b/library/std/src/sys/pal/windows/c/bindings.txt
@@ -2170,6 +2170,7 @@ GetFileType
 GETFINALPATHNAMEBYHANDLE_FLAGS
 GetFinalPathNameByHandleW
 GetFullPathNameW
+GetHostNameW
 GetLastError
 GetModuleFileNameW
 GetModuleHandleA
@@ -2270,6 +2271,7 @@ LPPROGRESS_ROUTINE
 LPPROGRESS_ROUTINE_CALLBACK_REASON
 LPTHREAD_START_ROUTINE
 LPWSAOVERLAPPED_COMPLETION_ROUTINE
+lstrlenW
 M128A
 MAX_PATH
 MAXIMUM_REPARSE_DATA_BUFFER_SIZE
diff --git a/library/std/src/sys/pal/windows/c/windows_sys.rs b/library/std/src/sys/pal/windows/c/windows_sys.rs
index 989a1246650..98f277b3378 100644
--- a/library/std/src/sys/pal/windows/c/windows_sys.rs
+++ b/library/std/src/sys/pal/windows/c/windows_sys.rs
@@ -49,6 +49,7 @@ windows_targets::link!("kernel32.dll" "system" fn GetFileSizeEx(hfile : HANDLE,
 windows_targets::link!("kernel32.dll" "system" fn GetFileType(hfile : HANDLE) -> FILE_TYPE);
 windows_targets::link!("kernel32.dll" "system" fn GetFinalPathNameByHandleW(hfile : HANDLE, lpszfilepath : PWSTR, cchfilepath : u32, dwflags : GETFINALPATHNAMEBYHANDLE_FLAGS) -> u32);
 windows_targets::link!("kernel32.dll" "system" fn GetFullPathNameW(lpfilename : PCWSTR, nbufferlength : u32, lpbuffer : PWSTR, lpfilepart : *mut PWSTR) -> u32);
+windows_targets::link!("ws2_32.dll" "system" fn GetHostNameW(name : PWSTR, namelen : i32) -> i32);
 windows_targets::link!("kernel32.dll" "system" fn GetLastError() -> WIN32_ERROR);
 windows_targets::link!("kernel32.dll" "system" fn GetModuleFileNameW(hmodule : HMODULE, lpfilename : PWSTR, nsize : u32) -> u32);
 windows_targets::link!("kernel32.dll" "system" fn GetModuleHandleA(lpmodulename : PCSTR) -> HMODULE);
@@ -134,6 +135,7 @@ windows_targets::link!("ws2_32.dll" "system" fn getsockname(s : SOCKET, name : *
 windows_targets::link!("ws2_32.dll" "system" fn getsockopt(s : SOCKET, level : i32, optname : i32, optval : PSTR, optlen : *mut i32) -> i32);
 windows_targets::link!("ws2_32.dll" "system" fn ioctlsocket(s : SOCKET, cmd : i32, argp : *mut u32) -> i32);
 windows_targets::link!("ws2_32.dll" "system" fn listen(s : SOCKET, backlog : i32) -> i32);
+windows_targets::link!("kernel32.dll" "system" fn lstrlenW(lpstring : PCWSTR) -> i32);
 windows_targets::link!("ws2_32.dll" "system" fn recv(s : SOCKET, buf : PSTR, len : i32, flags : SEND_RECV_FLAGS) -> i32);
 windows_targets::link!("ws2_32.dll" "system" fn recvfrom(s : SOCKET, buf : PSTR, len : i32, flags : i32, from : *mut SOCKADDR, fromlen : *mut i32) -> i32);
 windows_targets::link!("ws2_32.dll" "system" fn select(nfds : i32, readfds : *mut FD_SET, writefds : *mut FD_SET, exceptfds : *mut FD_SET, timeout : *const TIMEVAL) -> i32);
diff --git a/library/std/src/sys/pal/windows/mod.rs b/library/std/src/sys/pal/windows/mod.rs
index 3b6a86cbc8f..18ab3498267 100644
--- a/library/std/src/sys/pal/windows/mod.rs
+++ b/library/std/src/sys/pal/windows/mod.rs
@@ -20,10 +20,10 @@ pub mod futex;
 pub mod handle;
 pub mod os;
 pub mod pipe;
-pub mod thread;
 pub mod time;
 cfg_select! {
-    not(target_vendor = "uwp") => {
+    // We don't care about printing nice error messages for panic=immediate-abort
+    all(not(target_vendor = "uwp"), not(panic = "immediate-abort")) => {
         pub mod stack_overflow;
     }
     _ => {
@@ -31,6 +31,7 @@ cfg_select! {
         pub use self::stack_overflow_uwp as stack_overflow;
     }
 }
+pub mod winsock;
 
 /// Map a [`Result<T, WinError>`] to [`io::Result<T>`](crate::io::Result<T>).
 pub trait IoResult<T> {
@@ -48,9 +49,9 @@ pub unsafe fn init(_argc: isize, _argv: *const *const u8, _sigpipe: u8) {
     unsafe {
         stack_overflow::init();
 
-        // Normally, `thread::spawn` will call `Thread::set_name` but since this thread already
+        // Normally, `thread::spawn` will call `set_name` but since this thread already
         // exists, we have to call it ourselves.
-        thread::Thread::set_name_wide(wide_str!("main"));
+        crate::sys::thread::set_name_wide(wide_str!("main"));
     }
 }
 
diff --git a/library/std/src/sys/pal/windows/time.rs b/library/std/src/sys/pal/windows/time.rs
index a948c07e0a3..0d31b80e56a 100644
--- a/library/std/src/sys/pal/windows/time.rs
+++ b/library/std/src/sys/pal/windows/time.rs
@@ -72,8 +72,7 @@ impl SystemTime {
         }
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    const fn from_intervals(intervals: i64) -> SystemTime {
+    fn from_intervals(intervals: i64) -> SystemTime {
         SystemTime {
             t: c::FILETIME {
                 dwLowDateTime: intervals as u32,
@@ -82,13 +81,11 @@ impl SystemTime {
         }
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    const fn intervals(&self) -> i64 {
+    fn intervals(&self) -> i64 {
         (self.t.dwLowDateTime as i64) | ((self.t.dwHighDateTime as i64) << 32)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
         let me = self.intervals();
         let other = other.intervals();
         if me >= other {
@@ -98,14 +95,12 @@ impl SystemTime {
         }
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
         let intervals = self.intervals().checked_add(checked_dur2intervals(other)?)?;
         Some(SystemTime::from_intervals(intervals))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
         let intervals = self.intervals().checked_sub(checked_dur2intervals(other)?)?;
         Some(SystemTime::from_intervals(intervals))
     }
@@ -155,18 +150,15 @@ impl Hash for SystemTime {
     }
 }
 
-#[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-const fn checked_dur2intervals(dur: &Duration) -> Option<i64> {
-    // FIXME: const TryInto
-    let secs = dur
-        .as_secs()
+fn checked_dur2intervals(dur: &Duration) -> Option<i64> {
+    dur.as_secs()
         .checked_mul(INTERVALS_PER_SEC)?
-        .checked_add(dur.subsec_nanos() as u64 / 100)?;
-    if secs <= i64::MAX as u64 { Some(secs.cast_signed()) } else { None }
+        .checked_add(dur.subsec_nanos() as u64 / 100)?
+        .try_into()
+        .ok()
 }
 
-#[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-const fn intervals2dur(intervals: u64) -> Duration {
+fn intervals2dur(intervals: u64) -> Duration {
     Duration::new(intervals / INTERVALS_PER_SEC, ((intervals % INTERVALS_PER_SEC) * 100) as u32)
 }
 
@@ -232,7 +224,7 @@ mod perf_counter {
 }
 
 /// A timer you can wait on.
-pub(super) struct WaitableTimer {
+pub(crate) struct WaitableTimer {
     handle: c::HANDLE,
 }
 impl WaitableTimer {
diff --git a/library/std/src/sys/pal/windows/winsock.rs b/library/std/src/sys/pal/windows/winsock.rs
new file mode 100644
index 00000000000..b110a43ef3a
--- /dev/null
+++ b/library/std/src/sys/pal/windows/winsock.rs
@@ -0,0 +1,80 @@
+use super::c;
+use crate::ffi::c_int;
+use crate::sync::atomic::Atomic;
+use crate::sync::atomic::Ordering::{AcqRel, Relaxed};
+use crate::{io, mem};
+
+static WSA_STARTED: Atomic<bool> = Atomic::<bool>::new(false);
+
+/// Checks whether the Windows socket interface has been started already, and
+/// if not, starts it.
+#[inline]
+pub fn startup() {
+    if !WSA_STARTED.load(Relaxed) {
+        wsa_startup();
+    }
+}
+
+#[cold]
+fn wsa_startup() {
+    unsafe {
+        let mut data: c::WSADATA = mem::zeroed();
+        let ret = c::WSAStartup(
+            0x202, // version 2.2
+            &mut data,
+        );
+        assert_eq!(ret, 0);
+        if WSA_STARTED.swap(true, AcqRel) {
+            // If another thread raced with us and called WSAStartup first then call
+            // WSACleanup so it's as though WSAStartup was only called once.
+            c::WSACleanup();
+        }
+    }
+}
+
+pub fn cleanup() {
+    // We don't need to call WSACleanup here because exiting the process will cause
+    // the OS to clean everything for us, which is faster than doing it manually.
+    // See #141799.
+}
+
+/// Returns the last error from the Windows socket interface.
+pub fn last_error() -> io::Error {
+    io::Error::from_raw_os_error(unsafe { c::WSAGetLastError() })
+}
+
+#[doc(hidden)]
+pub trait IsMinusOne {
+    fn is_minus_one(&self) -> bool;
+}
+
+macro_rules! impl_is_minus_one {
+    ($($t:ident)*) => ($(impl IsMinusOne for $t {
+        fn is_minus_one(&self) -> bool {
+            *self == -1
+        }
+    })*)
+}
+
+impl_is_minus_one! { i8 i16 i32 i64 isize }
+
+/// Checks if the signed integer is the Windows constant `SOCKET_ERROR` (-1)
+/// and if so, returns the last error from the Windows socket interface. This
+/// function must be called before another call to the socket API is made.
+pub fn cvt<T: IsMinusOne>(t: T) -> io::Result<T> {
+    if t.is_minus_one() { Err(last_error()) } else { Ok(t) }
+}
+
+/// A variant of `cvt` for `getaddrinfo` which return 0 for a success.
+pub fn cvt_gai(err: c_int) -> io::Result<()> {
+    if err == 0 { Ok(()) } else { Err(last_error()) }
+}
+
+/// Just to provide the same interface as sys/pal/unix/net.rs
+pub fn cvt_r<T, F>(mut f: F) -> io::Result<T>
+where
+    T: IsMinusOne,
+    F: FnMut() -> T,
+{
+    cvt(f())
+}
diff --git a/library/std/src/sys/pal/xous/mod.rs b/library/std/src/sys/pal/xous/mod.rs
index 042c4ff862f..e673157e0eb 100644
--- a/library/std/src/sys/pal/xous/mod.rs
+++ b/library/std/src/sys/pal/xous/mod.rs
@@ -5,7 +5,6 @@ use crate::os::xous::ffi::exit;
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
-pub mod thread;
 pub mod time;
 
 #[path = "../unsupported/common.rs"]
diff --git a/library/std/src/sys/pal/xous/time.rs b/library/std/src/sys/pal/xous/time.rs
index d737416436e..ae8be81c0b7 100644
--- a/library/std/src/sys/pal/xous/time.rs
+++ b/library/std/src/sys/pal/xous/time.rs
@@ -43,22 +43,15 @@ impl SystemTime {
         SystemTime { 0: Duration::from_millis((upper as u64) << 32 | lower as u64) }
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
-        // FIXME: ok_or_else with const closures
-        match self.0.checked_sub(other.0) {
-            Some(duration) => Ok(duration),
-            None => Err(other.0 - self.0),
-        }
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+        self.0.checked_sub(other.0).ok_or_else(|| other.0 - self.0)
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_add(*other)?))
     }
 
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
         Some(SystemTime(self.0.checked_sub(*other)?))
     }
 }
diff --git a/library/std/src/sys/pal/zkvm/mod.rs b/library/std/src/sys/pal/zkvm/mod.rs
index e1efa240685..9069c8d12fa 100644
--- a/library/std/src/sys/pal/zkvm/mod.rs
+++ b/library/std/src/sys/pal/zkvm/mod.rs
@@ -14,8 +14,6 @@ pub mod abi;
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
-#[path = "../unsupported/thread.rs"]
-pub mod thread;
 #[path = "../unsupported/time.rs"]
 pub mod time;
 
diff --git a/library/std/src/sys/process/mod.rs b/library/std/src/sys/process/mod.rs
index 9ef5496e57a..a1ed0cd2cdd 100644
--- a/library/std/src/sys/process/mod.rs
+++ b/library/std/src/sys/process/mod.rs
@@ -24,7 +24,7 @@ mod env;
 
 pub use env::CommandEnvs;
 pub use imp::{
-    Command, CommandArgs, EnvKey, ExitCode, ExitStatus, ExitStatusError, Process, Stdio, StdioPipes,
+    Command, CommandArgs, EnvKey, ExitCode, ExitStatus, ExitStatusError, Process, Stdio,
 };
 
 #[cfg(any(
diff --git a/library/std/src/sys/process/uefi.rs b/library/std/src/sys/process/uefi.rs
index 4864c586988..11c8b682bb9 100644
--- a/library/std/src/sys/process/uefi.rs
+++ b/library/std/src/sys/process/uefi.rs
@@ -6,6 +6,7 @@ pub use crate::ffi::OsString as EnvKey;
 use crate::ffi::{OsStr, OsString};
 use crate::num::{NonZero, NonZeroI32};
 use crate::path::Path;
+use crate::process::StdioPipes;
 use crate::sys::fs::File;
 use crate::sys::pal::helpers;
 use crate::sys::pal::os::error_string;
@@ -27,14 +28,6 @@ pub struct Command {
     env: CommandEnv,
 }
 
-// passed back to std::process with the pipes connected to the child, if any
-// were requested
-pub struct StdioPipes {
-    pub stdin: Option<AnonPipe>,
-    pub stdout: Option<AnonPipe>,
-    pub stderr: Option<AnonPipe>,
-}
-
 #[derive(Copy, Clone, Debug)]
 pub enum Stdio {
     Inherit,
diff --git a/library/std/src/sys/process/unix/common.rs b/library/std/src/sys/process/unix/common.rs
index ea45b08e90a..1d5909e99ba 100644
--- a/library/std/src/sys/process/unix/common.rs
+++ b/library/std/src/sys/process/unix/common.rs
@@ -9,6 +9,7 @@ use crate::collections::BTreeMap;
 use crate::ffi::{CStr, CString, OsStr, OsString};
 use crate::os::unix::prelude::*;
 use crate::path::Path;
+use crate::process::StdioPipes;
 use crate::sys::fd::FileDesc;
 use crate::sys::fs::File;
 #[cfg(not(target_os = "fuchsia"))]
@@ -104,14 +105,6 @@ pub struct Command {
     setsid: bool,
 }
 
-// passed back to std::process with the pipes connected to the child, if any
-// were requested
-pub struct StdioPipes {
-    pub stdin: Option<AnonPipe>,
-    pub stdout: Option<AnonPipe>,
-    pub stderr: Option<AnonPipe>,
-}
-
 // passed to do_exec() with configuration of what the child stdio should look
 // like
 #[cfg_attr(target_os = "vita", allow(dead_code))]
diff --git a/library/std/src/sys/process/unix/fuchsia.rs b/library/std/src/sys/process/unix/fuchsia.rs
index d71be510b6a..3fae5ec1468 100644
--- a/library/std/src/sys/process/unix/fuchsia.rs
+++ b/library/std/src/sys/process/unix/fuchsia.rs
@@ -2,6 +2,7 @@ use libc::{c_int, size_t};
 
 use super::common::*;
 use crate::num::NonZero;
+use crate::process::StdioPipes;
 use crate::sys::pal::fuchsia::*;
 use crate::{fmt, io, mem, ptr};
 
diff --git a/library/std/src/sys/process/unix/mod.rs b/library/std/src/sys/process/unix/mod.rs
index b4cf060fba9..cda1bf74f1c 100644
--- a/library/std/src/sys/process/unix/mod.rs
+++ b/library/std/src/sys/process/unix/mod.rs
@@ -23,5 +23,5 @@ cfg_select! {
 
 pub use imp::{ExitStatus, ExitStatusError, Process};
 
-pub use self::common::{Command, CommandArgs, ExitCode, Stdio, StdioPipes};
+pub use self::common::{Command, CommandArgs, ExitCode, Stdio};
 pub use crate::ffi::OsString as EnvKey;
diff --git a/library/std/src/sys/process/unix/unix.rs b/library/std/src/sys/process/unix/unix.rs
index 11d48878727..7d944f2f7ee 100644
--- a/library/std/src/sys/process/unix/unix.rs
+++ b/library/std/src/sys/process/unix/unix.rs
@@ -13,6 +13,7 @@ use libc::{gid_t, uid_t};
 use super::common::*;
 use crate::io::{self, Error, ErrorKind};
 use crate::num::NonZero;
+use crate::process::StdioPipes;
 use crate::sys::cvt;
 #[cfg(target_os = "linux")]
 use crate::sys::pal::linux::pidfd::PidFd;
diff --git a/library/std/src/sys/process/unix/unix/tests.rs b/library/std/src/sys/process/unix/unix/tests.rs
index f4d6ac6b4e3..663ba61f966 100644
--- a/library/std/src/sys/process/unix/unix/tests.rs
+++ b/library/std/src/sys/process/unix/unix/tests.rs
@@ -51,6 +51,7 @@ fn exitstatus_display_tests() {
 
 #[test]
 #[cfg_attr(target_os = "emscripten", ignore)]
+#[cfg_attr(any(target_os = "tvos", target_os = "watchos"), ignore = "fork is prohibited")]
 fn test_command_fork_no_unwind() {
     let got = catch_unwind(|| {
         let mut c = Command::new("echo");
diff --git a/library/std/src/sys/process/unix/unsupported.rs b/library/std/src/sys/process/unix/unsupported.rs
index 87403cd50f8..9bda394f246 100644
--- a/library/std/src/sys/process/unix/unsupported.rs
+++ b/library/std/src/sys/process/unix/unsupported.rs
@@ -3,6 +3,7 @@ use libc::{c_int, pid_t};
 use super::common::*;
 use crate::io;
 use crate::num::NonZero;
+use crate::process::StdioPipes;
 use crate::sys::pal::unsupported::*;
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/library/std/src/sys/process/unix/vxworks.rs b/library/std/src/sys/process/unix/vxworks.rs
index 2275cbb946a..346ca6d74c9 100644
--- a/library/std/src/sys/process/unix/vxworks.rs
+++ b/library/std/src/sys/process/unix/vxworks.rs
@@ -4,8 +4,8 @@ use libc::{self, RTP_ID, c_char, c_int};
 use super::common::*;
 use crate::io::{self, ErrorKind};
 use crate::num::NonZero;
-use crate::sys::cvt;
-use crate::sys::pal::thread;
+use crate::process::StdioPipes;
+use crate::sys::{cvt, thread};
 use crate::{fmt, sys};
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/library/std/src/sys/process/unsupported.rs b/library/std/src/sys/process/unsupported.rs
index 469922c78ac..636465b68e5 100644
--- a/library/std/src/sys/process/unsupported.rs
+++ b/library/std/src/sys/process/unsupported.rs
@@ -3,6 +3,7 @@ pub use crate::ffi::OsString as EnvKey;
 use crate::ffi::{OsStr, OsString};
 use crate::num::NonZero;
 use crate::path::Path;
+use crate::process::StdioPipes;
 use crate::sys::fs::File;
 use crate::sys::pipe::AnonPipe;
 use crate::sys::unsupported;
@@ -23,14 +24,6 @@ pub struct Command {
     stderr: Option<Stdio>,
 }
 
-// passed back to std::process with the pipes connected to the child, if any
-// were requested
-pub struct StdioPipes {
-    pub stdin: Option<AnonPipe>,
-    pub stdout: Option<AnonPipe>,
-    pub stderr: Option<AnonPipe>,
-}
-
 #[derive(Debug)]
 pub enum Stdio {
     Inherit,
diff --git a/library/std/src/sys/process/windows.rs b/library/std/src/sys/process/windows.rs
index f9e15b82475..1f2001bdc20 100644
--- a/library/std/src/sys/process/windows.rs
+++ b/library/std/src/sys/process/windows.rs
@@ -15,6 +15,7 @@ use crate::os::windows::ffi::{OsStrExt, OsStringExt};
 use crate::os::windows::io::{AsHandle, AsRawHandle, BorrowedHandle, FromRawHandle, IntoRawHandle};
 use crate::os::windows::process::ProcThreadAttributeList;
 use crate::path::{Path, PathBuf};
+use crate::process::StdioPipes;
 use crate::sync::Mutex;
 use crate::sys::args::{self, Arg};
 use crate::sys::c::{self, EXIT_FAILURE, EXIT_SUCCESS};
@@ -169,12 +170,6 @@ pub enum Stdio {
     Handle(Handle),
 }
 
-pub struct StdioPipes {
-    pub stdin: Option<AnonPipe>,
-    pub stdout: Option<AnonPipe>,
-    pub stderr: Option<AnonPipe>,
-}
-
 impl Command {
     pub fn new(program: &OsStr) -> Command {
         Command {
diff --git a/library/std/src/sys/random/mod.rs b/library/std/src/sys/random/mod.rs
index 1e0eec07b50..3c5a4c82a9f 100644
--- a/library/std/src/sys/random/mod.rs
+++ b/library/std/src/sys/random/mod.rs
@@ -101,6 +101,7 @@ cfg_select! {
     any(
         all(target_family = "wasm", target_os = "unknown"),
         target_os = "xous",
+        target_os = "vexos",
     ) => {
         // FIXME: finally remove std support for wasm32-unknown-unknown
         // FIXME: add random data generation to xous
@@ -116,6 +117,7 @@ cfg_select! {
     all(target_family = "wasm", target_os = "unknown"),
     all(target_os = "wasi", target_env = "p2"),
     target_os = "xous",
+    target_os = "vexos",
 )))]
 pub fn hashmap_random_keys() -> (u64, u64) {
     let mut buf = [0; 16];
diff --git a/library/std/src/sys/stdio/mod.rs b/library/std/src/sys/stdio/mod.rs
index 7436e4d9de4..404ac877926 100644
--- a/library/std/src/sys/stdio/mod.rs
+++ b/library/std/src/sys/stdio/mod.rs
@@ -29,6 +29,10 @@ cfg_select! {
         mod uefi;
         pub use uefi::*;
     }
+    target_os = "vexos" => {
+        mod vexos;
+        pub use vexos::*;
+    }
     all(target_os = "wasi", target_env = "p1") => {
         mod wasip1;
         pub use wasip1::*;
diff --git a/library/std/src/sys/stdio/vexos.rs b/library/std/src/sys/stdio/vexos.rs
new file mode 100644
index 00000000000..9a391feb7a8
--- /dev/null
+++ b/library/std/src/sys/stdio/vexos.rs
@@ -0,0 +1,100 @@
+use crate::io;
+
+pub struct Stdin;
+pub struct Stdout;
+pub type Stderr = Stdout;
+
+pub const STDIO_CHANNEL: u32 = 1;
+
+impl Stdin {
+    pub const fn new() -> Stdin {
+        Stdin
+    }
+}
+
+impl io::Read for Stdin {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let mut count = 0;
+
+        for out_byte in buf.iter_mut() {
+            let byte = unsafe { vex_sdk::vexSerialReadChar(STDIO_CHANNEL) };
+            if byte < 0 {
+                break;
+            }
+
+            *out_byte = byte as u8;
+            count += 1;
+        }
+
+        Ok(count)
+    }
+}
+
+impl Stdout {
+    pub const fn new() -> Stdout {
+        Stdout
+    }
+}
+
+impl io::Write for Stdout {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        let mut written = 0;
+
+        // HACK: VEXos holds an internal ringbuffer for serial writes that is flushed to USB1
+        // roughly every millisecond by `vexTasksRun`. For writes larger than 2048 bytes, we
+        // must block until that buffer is flushed to USB1 before writing the rest of `buf`.
+        //
+        // This is fairly nonstandard for a `write` implementation, but it avoids a guaranteed
+        // recursive panic when using macros such as `print!` to write large amounts of data
+        // (buf.len() > 2048) to stdout at once.
+        for chunk in buf.chunks(STDOUT_BUF_SIZE) {
+            if unsafe { vex_sdk::vexSerialWriteFree(STDIO_CHANNEL) as usize } < chunk.len() {
+                self.flush().unwrap();
+            }
+
+            let count: usize = unsafe {
+                vex_sdk::vexSerialWriteBuffer(STDIO_CHANNEL, chunk.as_ptr(), chunk.len() as u32)
+            }
+            .try_into()
+            .map_err(|_| {
+                io::const_error!(io::ErrorKind::Uncategorized, "internal write error occurred")
+            })?;
+
+            written += count;
+
+            // This is a sanity check to ensure that we don't end up with non-contiguous
+            // buffer writes. e.g. a chunk gets only partially written, but we continue
+            // attempting to write the remaining chunks.
+            //
+            // In practice, this should never really occur since the previous flush ensures
+            // enough space in FIFO to write the entire chunk to vexSerialWriteBuffer.
+            if count != chunk.len() {
+                break;
+            }
+        }
+
+        Ok(written)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        // This may block for up to a millisecond.
+        unsafe {
+            while (vex_sdk::vexSerialWriteFree(STDIO_CHANNEL) as usize) != STDOUT_BUF_SIZE {
+                vex_sdk::vexTasksRun();
+            }
+        }
+
+        Ok(())
+    }
+}
+
+pub const STDIN_BUF_SIZE: usize = 4096;
+pub const STDOUT_BUF_SIZE: usize = 2048;
+
+pub fn is_ebadf(_err: &io::Error) -> bool {
+    false
+}
+
+pub fn panic_output() -> Option<impl io::Write> {
+    Some(Stdout::new())
+}
diff --git a/library/std/src/sys/sync/once/queue.rs b/library/std/src/sys/sync/once/queue.rs
index 49e15d65f25..17d99cdb385 100644
--- a/library/std/src/sys/sync/once/queue.rs
+++ b/library/std/src/sys/sync/once/queue.rs
@@ -276,7 +276,9 @@ fn wait(
             // If the managing thread happens to signal and unpark us before we
             // can park ourselves, the result could be this thread never gets
             // unparked. Luckily `park` comes with the guarantee that if it got
-            // an `unpark` just before on an unparked thread it does not park.
+            // an `unpark` just before on an unparked thread it does not park. Crucially, we know
+            // the `unpark` must have happened between the `compare_exchange_weak` above and here,
+            // and there's no other `park` in that code that could steal our token.
             // SAFETY: we retrieved this handle on the current thread above.
             unsafe { node.thread.park() }
         }
diff --git a/library/std/src/sys/pal/hermit/thread.rs b/library/std/src/sys/thread/hermit.rs
index cc4734b6819..4d9f3b114c2 100644
--- a/library/std/src/sys/pal/hermit/thread.rs
+++ b/library/std/src/sys/thread/hermit.rs
@@ -1,10 +1,5 @@
-#![allow(dead_code)]
-
-use super::hermit_abi;
-use crate::ffi::CStr;
-use crate::mem::ManuallyDrop;
 use crate::num::NonZero;
-use crate::time::{Duration, Instant};
+use crate::time::Duration;
 use crate::{io, ptr};
 
 pub type Tid = hermit_abi::Tid;
@@ -68,57 +63,30 @@ impl Thread {
         }
     }
 
-    #[inline]
-    pub fn yield_now() {
-        unsafe {
-            hermit_abi::yield_now();
-        }
-    }
-
-    #[inline]
-    pub fn set_name(_name: &CStr) {
-        // nope
-    }
-
-    #[inline]
-    pub fn sleep(dur: Duration) {
-        let micros = dur.as_micros() + if dur.subsec_nanos() % 1_000 > 0 { 1 } else { 0 };
-        let micros = u64::try_from(micros).unwrap_or(u64::MAX);
-
-        unsafe {
-            hermit_abi::usleep(micros);
-        }
-    }
-
-    pub fn sleep_until(deadline: Instant) {
-        let now = Instant::now();
-
-        if let Some(delay) = deadline.checked_duration_since(now) {
-            Self::sleep(delay);
-        }
-    }
-
     pub fn join(self) {
         unsafe {
             let _ = hermit_abi::join(self.tid);
         }
     }
+}
 
-    #[inline]
-    pub fn id(&self) -> Tid {
-        self.tid
-    }
-
-    #[inline]
-    pub fn into_id(self) -> Tid {
-        ManuallyDrop::new(self).tid
-    }
+pub fn available_parallelism() -> io::Result<NonZero<usize>> {
+    unsafe { Ok(NonZero::new_unchecked(hermit_abi::available_parallelism())) }
 }
 
-pub(crate) fn current_os_id() -> Option<u64> {
-    None
+#[inline]
+pub fn sleep(dur: Duration) {
+    let micros = dur.as_micros() + if dur.subsec_nanos() % 1_000 > 0 { 1 } else { 0 };
+    let micros = u64::try_from(micros).unwrap_or(u64::MAX);
+
+    unsafe {
+        hermit_abi::usleep(micros);
+    }
 }
 
-pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    unsafe { Ok(NonZero::new_unchecked(hermit_abi::available_parallelism())) }
+#[inline]
+pub fn yield_now() {
+    unsafe {
+        hermit_abi::yield_now();
+    }
 }
diff --git a/library/std/src/sys/thread/mod.rs b/library/std/src/sys/thread/mod.rs
new file mode 100644
index 00000000000..3bd83dd760a
--- /dev/null
+++ b/library/std/src/sys/thread/mod.rs
@@ -0,0 +1,159 @@
+cfg_select! {
+    target_os = "hermit" => {
+        mod hermit;
+        pub use hermit::{Thread, available_parallelism, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{current_os_id, set_name};
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+        pub use sgx::{Thread, current_os_id, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+
+        // SGX should protect in-enclave data from outside attackers, so there
+        // must not be any data leakage to the OS, particularly no 1-1 mapping
+        // between SGX thread names and OS thread names. Hence `set_name` is
+        // intentionally a no-op.
+        //
+        // Note that the internally visible SGX thread name is already provided
+        // by the platform-agnostic Rust thread code. This can be observed in
+        // the [`std::thread::tests::test_named_thread`] test, which succeeds
+        // as-is with the SGX target.
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{available_parallelism, set_name};
+    }
+    target_os = "solid_asp3" => {
+        mod solid;
+        pub use solid::{Thread, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{available_parallelism, current_os_id, set_name};
+    }
+    target_os = "teeos" => {
+        mod teeos;
+        pub use teeos::{Thread, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{available_parallelism, current_os_id, set_name};
+    }
+    target_os = "uefi" => {
+        mod uefi;
+        pub use uefi::{available_parallelism, sleep};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{Thread, current_os_id, set_name, yield_now, DEFAULT_MIN_STACK_SIZE};
+    }
+    target_family = "unix" => {
+        mod unix;
+        pub use unix::{Thread, available_parallelism, current_os_id, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+        #[cfg(not(any(
+            target_env = "newlib",
+            target_os = "l4re",
+            target_os = "emscripten",
+            target_os = "redox",
+            target_os = "hurd",
+            target_os = "aix",
+        )))]
+        pub use unix::set_name;
+        #[cfg(any(
+            target_os = "freebsd",
+            target_os = "netbsd",
+            target_os = "linux",
+            target_os = "android",
+            target_os = "solaris",
+            target_os = "illumos",
+            target_os = "dragonfly",
+            target_os = "hurd",
+            target_os = "fuchsia",
+            target_os = "vxworks",
+        ))]
+        pub use unix::sleep_until;
+        #[expect(dead_code)]
+        mod unsupported;
+        #[cfg(any(
+            target_env = "newlib",
+            target_os = "l4re",
+            target_os = "emscripten",
+            target_os = "redox",
+            target_os = "hurd",
+            target_os = "aix",
+        ))]
+        pub use unsupported::set_name;
+    }
+    target_os = "vexos" => {
+        mod vexos;
+        pub use vexos::{sleep, yield_now};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{Thread, available_parallelism, current_os_id, set_name, DEFAULT_MIN_STACK_SIZE};
+    }
+    all(target_os = "wasi", target_env = "p1") => {
+        mod wasip1;
+        pub use wasip1::{DEFAULT_MIN_STACK_SIZE, sleep, yield_now};
+        #[cfg(target_feature = "atomics")]
+        pub use wasip1::{Thread, available_parallelism};
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{current_os_id, set_name};
+        #[cfg(not(target_feature = "atomics"))]
+        pub use unsupported::{Thread, available_parallelism};
+    }
+    all(target_os = "wasi", target_env = "p2") => {
+        mod wasip2;
+        pub use wasip2::{sleep, sleep_until};
+        #[expect(dead_code)]
+        mod unsupported;
+        // Note that unlike WASIp1 even if the wasm `atomics` feature is enabled
+        // there is no support for threads, not even experimentally, not even in
+        // wasi-libc. Thus this is unconditionally unsupported.
+        pub use unsupported::{Thread, available_parallelism, current_os_id, set_name, yield_now, DEFAULT_MIN_STACK_SIZE};
+    }
+    all(target_family = "wasm", target_feature = "atomics") => {
+        mod wasm;
+        pub use wasm::sleep;
+
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{Thread, available_parallelism, current_os_id, set_name, yield_now, DEFAULT_MIN_STACK_SIZE};
+    }
+    target_os = "windows" => {
+        mod windows;
+        pub use windows::{Thread, available_parallelism, current_os_id, set_name, set_name_wide, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+    }
+    target_os = "xous" => {
+        mod xous;
+        pub use xous::{Thread, available_parallelism, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+
+        #[expect(dead_code)]
+        mod unsupported;
+        pub use unsupported::{current_os_id, set_name};
+    }
+    _ => {
+        mod unsupported;
+        pub use unsupported::{Thread, available_parallelism, current_os_id, set_name, sleep, yield_now, DEFAULT_MIN_STACK_SIZE};
+    }
+}
+
+#[cfg(not(any(
+    target_os = "freebsd",
+    target_os = "netbsd",
+    target_os = "linux",
+    target_os = "android",
+    target_os = "solaris",
+    target_os = "illumos",
+    target_os = "dragonfly",
+    target_os = "hurd",
+    target_os = "fuchsia",
+    target_os = "vxworks",
+    all(target_os = "wasi", target_env = "p2"),
+)))]
+pub fn sleep_until(deadline: crate::time::Instant) {
+    use crate::time::Instant;
+
+    let now = Instant::now();
+
+    if let Some(delay) = deadline.checked_duration_since(now) {
+        sleep(delay);
+    }
+}
diff --git a/library/std/src/sys/pal/sgx/thread.rs b/library/std/src/sys/thread/sgx.rs
index 1f613badcd7..f20ef7d86b9 100644
--- a/library/std/src/sys/pal/sgx/thread.rs
+++ b/library/std/src/sys/thread/sgx.rs
@@ -1,11 +1,8 @@
 #![cfg_attr(test, allow(dead_code))] // why is this necessary?
 
-use super::abi::{thread, usercalls};
-use super::unsupported;
-use crate::ffi::CStr;
 use crate::io;
-use crate::num::NonZero;
-use crate::time::{Duration, Instant};
+use crate::sys::pal::abi::{thread, usercalls};
+use crate::time::Duration;
 
 pub struct Thread(task_queue::JoinHandle);
 
@@ -108,51 +105,27 @@ impl Thread {
         Ok(Thread(handle))
     }
 
-    pub(super) fn entry() -> JoinNotifier {
+    pub(crate) fn entry() -> JoinNotifier {
         let mut pending_tasks = task_queue::lock();
         let task = rtunwrap!(Some, pending_tasks.pop());
         drop(pending_tasks); // make sure to not hold the task queue lock longer than necessary
         task.run()
     }
 
-    pub fn yield_now() {
-        let wait_error = rtunwrap!(Err, usercalls::wait(0, usercalls::raw::WAIT_NO));
-        rtassert!(wait_error.kind() == io::ErrorKind::WouldBlock);
-    }
-
-    /// SGX should protect in-enclave data from the outside (attacker),
-    /// so there should be no data leakage to the OS,
-    /// and therefore also no 1-1 mapping between SGX thread names and OS thread names.
-    ///
-    /// This is why the method is intentionally No-Op.
-    pub fn set_name(_name: &CStr) {
-        // Note that the internally visible SGX thread name is already provided
-        // by the platform-agnostic (target-agnostic) Rust thread code.
-        // This can be observed in the [`std::thread::tests::test_named_thread`] test,
-        // which succeeds as-is with the SGX target.
-    }
-
-    pub fn sleep(dur: Duration) {
-        usercalls::wait_timeout(0, dur, || true);
-    }
-
-    pub fn sleep_until(deadline: Instant) {
-        let now = Instant::now();
-
-        if let Some(delay) = deadline.checked_duration_since(now) {
-            Self::sleep(delay);
-        }
-    }
-
     pub fn join(self) {
         self.0.wait();
     }
 }
 
-pub(crate) fn current_os_id() -> Option<u64> {
+pub fn current_os_id() -> Option<u64> {
     Some(thread::current().addr().get() as u64)
 }
 
-pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    unsupported()
+pub fn sleep(dur: Duration) {
+    usercalls::wait_timeout(0, dur, || true);
+}
+
+pub fn yield_now() {
+    let wait_error = rtunwrap!(Err, usercalls::wait(0, usercalls::raw::WAIT_NO));
+    rtassert!(wait_error.kind() == io::ErrorKind::WouldBlock);
 }
diff --git a/library/std/src/sys/pal/itron/thread.rs b/library/std/src/sys/thread/solid.rs
index 4e14cb3cbca..46a84faa802 100644
--- a/library/std/src/sys/pal/itron/thread.rs
+++ b/library/std/src/sys/thread/solid.rs
@@ -1,16 +1,14 @@
 //! Thread implementation backed by μITRON tasks. Assumes `acre_tsk` and
 //! `exd_tsk` are available.
 
-use super::error::{ItronError, expect_success, expect_success_aborting};
-use super::time::dur2reltims;
-use super::{abi, task};
 use crate::cell::UnsafeCell;
-use crate::ffi::CStr;
 use crate::mem::ManuallyDrop;
-use crate::num::NonZero;
 use crate::ptr::NonNull;
 use crate::sync::atomic::{Atomic, AtomicUsize, Ordering};
-use crate::time::{Duration, Instant};
+use crate::sys::pal::itron::error::{ItronError, expect_success, expect_success_aborting};
+use crate::sys::pal::itron::time::dur2reltims;
+use crate::sys::pal::itron::{abi, task};
+use crate::time::Duration;
 use crate::{hint, io};
 
 pub struct Thread {
@@ -195,28 +193,6 @@ impl Thread {
         Ok(Self { p_inner, task: new_task })
     }
 
-    pub fn yield_now() {
-        expect_success(unsafe { abi::rot_rdq(abi::TPRI_SELF) }, &"rot_rdq");
-    }
-
-    pub fn set_name(_name: &CStr) {
-        // nope
-    }
-
-    pub fn sleep(dur: Duration) {
-        for timeout in dur2reltims(dur) {
-            expect_success(unsafe { abi::dly_tsk(timeout) }, &"dly_tsk");
-        }
-    }
-
-    pub fn sleep_until(deadline: Instant) {
-        let now = Instant::now();
-
-        if let Some(delay) = deadline.checked_duration_since(now) {
-            Self::sleep(delay);
-        }
-    }
-
     pub fn join(self) {
         // Safety: `ThreadInner` is alive at this point
         let inner = unsafe { self.p_inner.as_ref() };
@@ -361,10 +337,12 @@ unsafe fn terminate_and_delete_current_task() -> ! {
     unsafe { crate::hint::unreachable_unchecked() };
 }
 
-pub(crate) fn current_os_id() -> Option<u64> {
-    None
+pub fn yield_now() {
+    expect_success(unsafe { abi::rot_rdq(abi::TPRI_SELF) }, &"rot_rdq");
 }
 
-pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    super::unsupported()
+pub fn sleep(dur: Duration) {
+    for timeout in dur2reltims(dur) {
+        expect_success(unsafe { abi::dly_tsk(timeout) }, &"dly_tsk");
+    }
 }
diff --git a/library/std/src/sys/pal/teeos/thread.rs b/library/std/src/sys/thread/teeos.rs
index 1812d11e692..cad100395c9 100644
--- a/library/std/src/sys/pal/teeos/thread.rs
+++ b/library/std/src/sys/thread/teeos.rs
@@ -1,12 +1,18 @@
-use crate::ffi::CStr;
 use crate::mem::{self, ManuallyDrop};
-use crate::num::NonZero;
 use crate::sys::os;
-use crate::time::{Duration, Instant};
+use crate::time::Duration;
 use crate::{cmp, io, ptr};
 
 pub const DEFAULT_MIN_STACK_SIZE: usize = 8 * 1024;
 
+unsafe extern "C" {
+    safe fn TEE_Wait(timeout: u32) -> u32;
+}
+
+fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
+    libc::PTHREAD_STACK_MIN.try_into().expect("Infallible")
+}
+
 pub struct Thread {
     id: libc::pthread_t,
 }
@@ -16,10 +22,6 @@ pub struct Thread {
 unsafe impl Send for Thread {}
 unsafe impl Sync for Thread {}
 
-unsafe extern "C" {
-    pub fn TEE_Wait(timeout: u32) -> u32;
-}
-
 impl Thread {
     // unsafe: see thread::Builder::spawn_unchecked for safety requirements
     pub unsafe fn new(
@@ -74,7 +76,7 @@ impl Thread {
         } else {
             // The new thread will start running earliest after the next yield.
             // We add a yield here, so that the user does not have to.
-            Thread::yield_now();
+            yield_now();
             Ok(Thread { id: native })
         };
 
@@ -91,36 +93,6 @@ impl Thread {
         }
     }
 
-    pub fn yield_now() {
-        let ret = unsafe { libc::sched_yield() };
-        debug_assert_eq!(ret, 0);
-    }
-
-    /// This does not do anything on teeos
-    pub fn set_name(_name: &CStr) {
-        // Both pthread_setname_np and prctl are not available to the TA,
-        // so we can't implement this currently. If the need arises please
-        // contact the teeos rustzone team.
-    }
-
-    /// only main thread could wait for sometime in teeos
-    pub fn sleep(dur: Duration) {
-        let sleep_millis = dur.as_millis();
-        let final_sleep: u32 =
-            if sleep_millis >= u32::MAX as u128 { u32::MAX } else { sleep_millis as u32 };
-        unsafe {
-            let _ = TEE_Wait(final_sleep);
-        }
-    }
-
-    pub fn sleep_until(deadline: Instant) {
-        let now = Instant::now();
-
-        if let Some(delay) = deadline.checked_duration_since(now) {
-            Self::sleep(delay);
-        }
-    }
-
     /// must join, because no pthread_detach supported
     pub fn join(self) {
         let id = self.into_id();
@@ -128,10 +100,6 @@ impl Thread {
         assert!(ret == 0, "failed to join thread: {}", io::Error::from_raw_os_error(ret));
     }
 
-    pub fn id(&self) -> libc::pthread_t {
-        self.id
-    }
-
     pub fn into_id(self) -> libc::pthread_t {
         ManuallyDrop::new(self).id
     }
@@ -144,16 +112,15 @@ impl Drop for Thread {
     }
 }
 
-pub(crate) fn current_os_id() -> Option<u64> {
-    None
-}
-
-// Note: Both `sched_getaffinity` and `sysconf` are available but not functional on
-// teeos, so this function always returns an Error!
-pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    Err(io::Error::UNKNOWN_THREAD_COUNT)
+pub fn yield_now() {
+    let ret = unsafe { libc::sched_yield() };
+    debug_assert_eq!(ret, 0);
 }
 
-fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
-    libc::PTHREAD_STACK_MIN.try_into().expect("Infallible")
+/// only main thread could wait for sometime in teeos
+pub fn sleep(dur: Duration) {
+    let sleep_millis = dur.as_millis();
+    let final_sleep: u32 =
+        if sleep_millis >= u32::MAX as u128 { u32::MAX } else { sleep_millis as u32 };
+    TEE_Wait(final_sleep);
 }
diff --git a/library/std/src/sys/thread/uefi.rs b/library/std/src/sys/thread/uefi.rs
new file mode 100644
index 00000000000..94f67d7ace2
--- /dev/null
+++ b/library/std/src/sys/thread/uefi.rs
@@ -0,0 +1,25 @@
+use crate::io;
+use crate::num::NonZero;
+use crate::ptr::NonNull;
+use crate::time::Duration;
+
+pub fn available_parallelism() -> io::Result<NonZero<usize>> {
+    // UEFI is single threaded
+    Ok(NonZero::new(1).unwrap())
+}
+
+pub fn sleep(dur: Duration) {
+    let boot_services: NonNull<r_efi::efi::BootServices> =
+        crate::os::uefi::env::boot_services().expect("can't sleep").cast();
+    let mut dur_ms = dur.as_micros();
+    // ceil up to the nearest microsecond
+    if dur.subsec_nanos() % 1000 > 0 {
+        dur_ms += 1;
+    }
+
+    while dur_ms > 0 {
+        let ms = crate::cmp::min(dur_ms, usize::MAX as u128);
+        let _ = unsafe { ((*boot_services.as_ptr()).stall)(ms as usize) };
+        dur_ms -= ms;
+    }
+}
diff --git a/library/std/src/sys/pal/unix/thread.rs b/library/std/src/sys/thread/unix.rs
index 3389b8c0c8a..2d2c4f90212 100644
--- a/library/std/src/sys/pal/unix/thread.rs
+++ b/library/std/src/sys/thread/unix.rs
@@ -1,3 +1,11 @@
+#[cfg(not(any(
+    target_env = "newlib",
+    target_os = "l4re",
+    target_os = "emscripten",
+    target_os = "redox",
+    target_os = "hurd",
+    target_os = "aix",
+)))]
 use crate::ffi::CStr;
 use crate::mem::{self, ManuallyDrop};
 use crate::num::NonZero;
@@ -6,7 +14,7 @@ use crate::sys::weak::dlsym;
 #[cfg(any(target_os = "solaris", target_os = "illumos", target_os = "nto",))]
 use crate::sys::weak::weak;
 use crate::sys::{os, stack_overflow};
-use crate::time::{Duration, Instant};
+use crate::time::Duration;
 use crate::{cmp, io, ptr};
 #[cfg(not(any(
     target_os = "l4re",
@@ -121,273 +129,6 @@ impl Thread {
         }
     }
 
-    pub fn yield_now() {
-        let ret = unsafe { libc::sched_yield() };
-        debug_assert_eq!(ret, 0);
-    }
-
-    #[cfg(target_os = "android")]
-    pub fn set_name(name: &CStr) {
-        const PR_SET_NAME: libc::c_int = 15;
-        unsafe {
-            let res = libc::prctl(
-                PR_SET_NAME,
-                name.as_ptr(),
-                0 as libc::c_ulong,
-                0 as libc::c_ulong,
-                0 as libc::c_ulong,
-            );
-            // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
-            debug_assert_eq!(res, 0);
-        }
-    }
-
-    #[cfg(any(
-        target_os = "linux",
-        target_os = "freebsd",
-        target_os = "dragonfly",
-        target_os = "nuttx",
-        target_os = "cygwin"
-    ))]
-    pub fn set_name(name: &CStr) {
-        unsafe {
-            cfg_select! {
-                any(target_os = "linux", target_os = "cygwin") => {
-                    // Linux and Cygwin limits the allowed length of the name.
-                    const TASK_COMM_LEN: usize = 16;
-                    let name = truncate_cstr::<{ TASK_COMM_LEN }>(name);
-                }
-                _ => {
-                    // FreeBSD, DragonFly BSD and NuttX do not enforce length limits.
-                }
-            };
-            // Available since glibc 2.12, musl 1.1.16, and uClibc 1.0.20 for Linux,
-            // FreeBSD 12.2 and 13.0, and DragonFly BSD 6.0.
-            let res = libc::pthread_setname_np(libc::pthread_self(), name.as_ptr());
-            // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
-            debug_assert_eq!(res, 0);
-        }
-    }
-
-    #[cfg(target_os = "openbsd")]
-    pub fn set_name(name: &CStr) {
-        unsafe {
-            libc::pthread_set_name_np(libc::pthread_self(), name.as_ptr());
-        }
-    }
-
-    #[cfg(target_vendor = "apple")]
-    pub fn set_name(name: &CStr) {
-        unsafe {
-            let name = truncate_cstr::<{ libc::MAXTHREADNAMESIZE }>(name);
-            let res = libc::pthread_setname_np(name.as_ptr());
-            // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
-            debug_assert_eq!(res, 0);
-        }
-    }
-
-    #[cfg(target_os = "netbsd")]
-    pub fn set_name(name: &CStr) {
-        unsafe {
-            let res = libc::pthread_setname_np(
-                libc::pthread_self(),
-                c"%s".as_ptr(),
-                name.as_ptr() as *mut libc::c_void,
-            );
-            debug_assert_eq!(res, 0);
-        }
-    }
-
-    #[cfg(any(target_os = "solaris", target_os = "illumos", target_os = "nto"))]
-    pub fn set_name(name: &CStr) {
-        weak!(
-            fn pthread_setname_np(
-                thread: libc::pthread_t,
-                name: *const libc::c_char,
-            ) -> libc::c_int;
-        );
-
-        if let Some(f) = pthread_setname_np.get() {
-            #[cfg(target_os = "nto")]
-            const THREAD_NAME_MAX: usize = libc::_NTO_THREAD_NAME_MAX as usize;
-            #[cfg(any(target_os = "solaris", target_os = "illumos"))]
-            const THREAD_NAME_MAX: usize = 32;
-
-            let name = truncate_cstr::<{ THREAD_NAME_MAX }>(name);
-            let res = unsafe { f(libc::pthread_self(), name.as_ptr()) };
-            debug_assert_eq!(res, 0);
-        }
-    }
-
-    #[cfg(target_os = "fuchsia")]
-    pub fn set_name(name: &CStr) {
-        use super::fuchsia::*;
-        unsafe {
-            zx_object_set_property(
-                zx_thread_self(),
-                ZX_PROP_NAME,
-                name.as_ptr() as *const libc::c_void,
-                name.to_bytes().len(),
-            );
-        }
-    }
-
-    #[cfg(target_os = "haiku")]
-    pub fn set_name(name: &CStr) {
-        unsafe {
-            let thread_self = libc::find_thread(ptr::null_mut());
-            let res = libc::rename_thread(thread_self, name.as_ptr());
-            // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
-            debug_assert_eq!(res, libc::B_OK);
-        }
-    }
-
-    #[cfg(target_os = "vxworks")]
-    pub fn set_name(name: &CStr) {
-        let mut name = truncate_cstr::<{ (libc::VX_TASK_RENAME_LENGTH - 1) as usize }>(name);
-        let res = unsafe { libc::taskNameSet(libc::taskIdSelf(), name.as_mut_ptr()) };
-        debug_assert_eq!(res, libc::OK);
-    }
-
-    #[cfg(any(
-        target_env = "newlib",
-        target_os = "l4re",
-        target_os = "emscripten",
-        target_os = "redox",
-        target_os = "hurd",
-        target_os = "aix",
-    ))]
-    pub fn set_name(_name: &CStr) {
-        // Newlib and Emscripten have no way to set a thread name.
-    }
-
-    #[cfg(not(target_os = "espidf"))]
-    pub fn sleep(dur: Duration) {
-        let mut secs = dur.as_secs();
-        let mut nsecs = dur.subsec_nanos() as _;
-
-        // If we're awoken with a signal then the return value will be -1 and
-        // nanosleep will fill in `ts` with the remaining time.
-        unsafe {
-            while secs > 0 || nsecs > 0 {
-                let mut ts = libc::timespec {
-                    tv_sec: cmp::min(libc::time_t::MAX as u64, secs) as libc::time_t,
-                    tv_nsec: nsecs,
-                };
-                secs -= ts.tv_sec as u64;
-                let ts_ptr = &raw mut ts;
-                if libc::nanosleep(ts_ptr, ts_ptr) == -1 {
-                    assert_eq!(os::errno(), libc::EINTR);
-                    secs += ts.tv_sec as u64;
-                    nsecs = ts.tv_nsec;
-                } else {
-                    nsecs = 0;
-                }
-            }
-        }
-    }
-
-    #[cfg(target_os = "espidf")]
-    pub fn sleep(dur: Duration) {
-        // ESP-IDF does not have `nanosleep`, so we use `usleep` instead.
-        // As per the documentation of `usleep`, it is expected to support
-        // sleep times as big as at least up to 1 second.
-        //
-        // ESP-IDF does support almost up to `u32::MAX`, but due to a potential integer overflow in its
-        // `usleep` implementation
-        // (https://github.com/espressif/esp-idf/blob/d7ca8b94c852052e3bc33292287ef4dd62c9eeb1/components/newlib/time.c#L210),
-        // we limit the sleep time to the maximum one that would not cause the underlying `usleep` implementation to overflow
-        // (`portTICK_PERIOD_MS` can be anything between 1 to 1000, and is 10 by default).
-        const MAX_MICROS: u32 = u32::MAX - 1_000_000 - 1;
-
-        // Add any nanoseconds smaller than a microsecond as an extra microsecond
-        // so as to comply with the `std::thread::sleep` contract which mandates
-        // implementations to sleep for _at least_ the provided `dur`.
-        // We can't overflow `micros` as it is a `u128`, while `Duration` is a pair of
-        // (`u64` secs, `u32` nanos), where the nanos are strictly smaller than 1 second
-        // (i.e. < 1_000_000_000)
-        let mut micros = dur.as_micros() + if dur.subsec_nanos() % 1_000 > 0 { 1 } else { 0 };
-
-        while micros > 0 {
-            let st = if micros > MAX_MICROS as u128 { MAX_MICROS } else { micros as u32 };
-            unsafe {
-                libc::usleep(st);
-            }
-
-            micros -= st as u128;
-        }
-    }
-
-    // Any unix that has clock_nanosleep
-    // If this list changes update the MIRI chock_nanosleep shim
-    #[cfg(any(
-        target_os = "freebsd",
-        target_os = "netbsd",
-        target_os = "linux",
-        target_os = "android",
-        target_os = "solaris",
-        target_os = "illumos",
-        target_os = "dragonfly",
-        target_os = "hurd",
-        target_os = "fuchsia",
-        target_os = "vxworks",
-    ))]
-    pub fn sleep_until(deadline: Instant) {
-        let Some(ts) = deadline.into_inner().into_timespec().to_timespec() else {
-            // The deadline is further in the future then can be passed to
-            // clock_nanosleep. We have to use Self::sleep instead. This might
-            // happen on 32 bit platforms, especially closer to 2038.
-            let now = Instant::now();
-            if let Some(delay) = deadline.checked_duration_since(now) {
-                Self::sleep(delay);
-            }
-            return;
-        };
-
-        unsafe {
-            // When we get interrupted (res = EINTR) call clock_nanosleep again
-            loop {
-                let res = libc::clock_nanosleep(
-                    super::time::Instant::CLOCK_ID,
-                    libc::TIMER_ABSTIME,
-                    &ts,
-                    core::ptr::null_mut(), // not required with TIMER_ABSTIME
-                );
-
-                if res == 0 {
-                    break;
-                } else {
-                    assert_eq!(
-                        res,
-                        libc::EINTR,
-                        "timespec is in range,
-                         clockid is valid and kernel should support it"
-                    );
-                }
-            }
-        }
-    }
-
-    // Any unix that does not have clock_nanosleep
-    #[cfg(not(any(
-        target_os = "freebsd",
-        target_os = "netbsd",
-        target_os = "linux",
-        target_os = "android",
-        target_os = "solaris",
-        target_os = "illumos",
-        target_os = "dragonfly",
-        target_os = "hurd",
-        target_os = "fuchsia",
-        target_os = "vxworks",
-    )))]
-    pub fn sleep_until(deadline: Instant) {
-        let now = Instant::now();
-        if let Some(delay) = deadline.checked_duration_since(now) {
-            Self::sleep(delay);
-        }
-    }
-
     pub fn join(self) {
         let id = self.into_id();
         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
@@ -410,84 +151,6 @@ impl Drop for Thread {
     }
 }
 
-pub(crate) fn current_os_id() -> Option<u64> {
-    // Most Unix platforms have a way to query an integer ID of the current thread, all with
-    // slightly different spellings.
-    //
-    // The OS thread ID is used rather than `pthread_self` so as to match what will be displayed
-    // for process inspection (debuggers, trace, `top`, etc.).
-    cfg_select! {
-        // Most platforms have a function returning a `pid_t` or int, which is an `i32`.
-        any(target_os = "android", target_os = "linux") => {
-            use crate::sys::weak::syscall;
-
-            // `libc::gettid` is only available on glibc 2.30+, but the syscall is available
-            // since Linux 2.4.11.
-            syscall!(fn gettid() -> libc::pid_t;);
-
-            // SAFETY: FFI call with no preconditions.
-            let id: libc::pid_t = unsafe { gettid() };
-            Some(id as u64)
-        }
-        target_os = "nto" => {
-            // SAFETY: FFI call with no preconditions.
-            let id: libc::pid_t = unsafe { libc::gettid() };
-            Some(id as u64)
-        }
-        target_os = "openbsd" => {
-            // SAFETY: FFI call with no preconditions.
-            let id: libc::pid_t = unsafe { libc::getthrid() };
-            Some(id as u64)
-        }
-        target_os = "freebsd" => {
-            // SAFETY: FFI call with no preconditions.
-            let id: libc::c_int = unsafe { libc::pthread_getthreadid_np() };
-            Some(id as u64)
-        }
-        target_os = "netbsd" => {
-            // SAFETY: FFI call with no preconditions.
-            let id: libc::lwpid_t = unsafe { libc::_lwp_self() };
-            Some(id as u64)
-        }
-        any(target_os = "illumos", target_os = "solaris") => {
-            // On Illumos and Solaris, the `pthread_t` is the same as the OS thread ID.
-            // SAFETY: FFI call with no preconditions.
-            let id: libc::pthread_t = unsafe { libc::pthread_self() };
-            Some(id as u64)
-        }
-        target_vendor = "apple" => {
-            // Apple allows querying arbitrary thread IDs, `thread=NULL` queries the current thread.
-            let mut id = 0u64;
-            // SAFETY: `thread_id` is a valid pointer, no other preconditions.
-            let status: libc::c_int = unsafe { libc::pthread_threadid_np(0, &mut id) };
-            if status == 0 {
-                Some(id)
-            } else {
-                None
-            }
-        }
-        // Other platforms don't have an OS thread ID or don't have a way to access it.
-        _ => None,
-    }
-}
-
-#[cfg(any(
-    target_os = "linux",
-    target_os = "nto",
-    target_os = "solaris",
-    target_os = "illumos",
-    target_os = "vxworks",
-    target_os = "cygwin",
-    target_vendor = "apple",
-))]
-fn truncate_cstr<const MAX_WITH_NUL: usize>(cstr: &CStr) -> [libc::c_char; MAX_WITH_NUL] {
-    let mut result = [0; MAX_WITH_NUL];
-    for (src, dst) in cstr.to_bytes().iter().zip(&mut result[..MAX_WITH_NUL - 1]) {
-        *dst = *src as libc::c_char;
-    }
-    result
-}
-
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     cfg_select! {
         any(
@@ -668,6 +331,318 @@ pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     }
 }
 
+pub fn current_os_id() -> Option<u64> {
+    // Most Unix platforms have a way to query an integer ID of the current thread, all with
+    // slightly different spellings.
+    //
+    // The OS thread ID is used rather than `pthread_self` so as to match what will be displayed
+    // for process inspection (debuggers, trace, `top`, etc.).
+    cfg_select! {
+        // Most platforms have a function returning a `pid_t` or int, which is an `i32`.
+        any(target_os = "android", target_os = "linux") => {
+            use crate::sys::pal::weak::syscall;
+
+            // `libc::gettid` is only available on glibc 2.30+, but the syscall is available
+            // since Linux 2.4.11.
+            syscall!(fn gettid() -> libc::pid_t;);
+
+            // SAFETY: FFI call with no preconditions.
+            let id: libc::pid_t = unsafe { gettid() };
+            Some(id as u64)
+        }
+        target_os = "nto" => {
+            // SAFETY: FFI call with no preconditions.
+            let id: libc::pid_t = unsafe { libc::gettid() };
+            Some(id as u64)
+        }
+        target_os = "openbsd" => {
+            // SAFETY: FFI call with no preconditions.
+            let id: libc::pid_t = unsafe { libc::getthrid() };
+            Some(id as u64)
+        }
+        target_os = "freebsd" => {
+            // SAFETY: FFI call with no preconditions.
+            let id: libc::c_int = unsafe { libc::pthread_getthreadid_np() };
+            Some(id as u64)
+        }
+        target_os = "netbsd" => {
+            // SAFETY: FFI call with no preconditions.
+            let id: libc::lwpid_t = unsafe { libc::_lwp_self() };
+            Some(id as u64)
+        }
+        any(target_os = "illumos", target_os = "solaris") => {
+            // On Illumos and Solaris, the `pthread_t` is the same as the OS thread ID.
+            // SAFETY: FFI call with no preconditions.
+            let id: libc::pthread_t = unsafe { libc::pthread_self() };
+            Some(id as u64)
+        }
+        target_vendor = "apple" => {
+            // Apple allows querying arbitrary thread IDs, `thread=NULL` queries the current thread.
+            let mut id = 0u64;
+            // SAFETY: `thread_id` is a valid pointer, no other preconditions.
+            let status: libc::c_int = unsafe { libc::pthread_threadid_np(0, &mut id) };
+            if status == 0 {
+                Some(id)
+            } else {
+                None
+            }
+        }
+        // Other platforms don't have an OS thread ID or don't have a way to access it.
+        _ => None,
+    }
+}
+
+#[cfg(any(
+    target_os = "linux",
+    target_os = "nto",
+    target_os = "solaris",
+    target_os = "illumos",
+    target_os = "vxworks",
+    target_os = "cygwin",
+    target_vendor = "apple",
+))]
+fn truncate_cstr<const MAX_WITH_NUL: usize>(cstr: &CStr) -> [libc::c_char; MAX_WITH_NUL] {
+    let mut result = [0; MAX_WITH_NUL];
+    for (src, dst) in cstr.to_bytes().iter().zip(&mut result[..MAX_WITH_NUL - 1]) {
+        *dst = *src as libc::c_char;
+    }
+    result
+}
+
+#[cfg(target_os = "android")]
+pub fn set_name(name: &CStr) {
+    const PR_SET_NAME: libc::c_int = 15;
+    unsafe {
+        let res = libc::prctl(
+            PR_SET_NAME,
+            name.as_ptr(),
+            0 as libc::c_ulong,
+            0 as libc::c_ulong,
+            0 as libc::c_ulong,
+        );
+        // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
+        debug_assert_eq!(res, 0);
+    }
+}
+
+#[cfg(any(
+    target_os = "linux",
+    target_os = "freebsd",
+    target_os = "dragonfly",
+    target_os = "nuttx",
+    target_os = "cygwin"
+))]
+pub fn set_name(name: &CStr) {
+    unsafe {
+        cfg_select! {
+            any(target_os = "linux", target_os = "cygwin") => {
+                // Linux and Cygwin limits the allowed length of the name.
+                const TASK_COMM_LEN: usize = 16;
+                let name = truncate_cstr::<{ TASK_COMM_LEN }>(name);
+            }
+            _ => {
+                // FreeBSD, DragonFly BSD and NuttX do not enforce length limits.
+            }
+        };
+        // Available since glibc 2.12, musl 1.1.16, and uClibc 1.0.20 for Linux,
+        // FreeBSD 12.2 and 13.0, and DragonFly BSD 6.0.
+        let res = libc::pthread_setname_np(libc::pthread_self(), name.as_ptr());
+        // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
+        debug_assert_eq!(res, 0);
+    }
+}
+
+#[cfg(target_os = "openbsd")]
+pub fn set_name(name: &CStr) {
+    unsafe {
+        libc::pthread_set_name_np(libc::pthread_self(), name.as_ptr());
+    }
+}
+
+#[cfg(target_vendor = "apple")]
+pub fn set_name(name: &CStr) {
+    unsafe {
+        let name = truncate_cstr::<{ libc::MAXTHREADNAMESIZE }>(name);
+        let res = libc::pthread_setname_np(name.as_ptr());
+        // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
+        debug_assert_eq!(res, 0);
+    }
+}
+
+#[cfg(target_os = "netbsd")]
+pub fn set_name(name: &CStr) {
+    unsafe {
+        let res = libc::pthread_setname_np(
+            libc::pthread_self(),
+            c"%s".as_ptr(),
+            name.as_ptr() as *mut libc::c_void,
+        );
+        debug_assert_eq!(res, 0);
+    }
+}
+
+#[cfg(any(target_os = "solaris", target_os = "illumos", target_os = "nto"))]
+pub fn set_name(name: &CStr) {
+    weak!(
+        fn pthread_setname_np(thread: libc::pthread_t, name: *const libc::c_char) -> libc::c_int;
+    );
+
+    if let Some(f) = pthread_setname_np.get() {
+        #[cfg(target_os = "nto")]
+        const THREAD_NAME_MAX: usize = libc::_NTO_THREAD_NAME_MAX as usize;
+        #[cfg(any(target_os = "solaris", target_os = "illumos"))]
+        const THREAD_NAME_MAX: usize = 32;
+
+        let name = truncate_cstr::<{ THREAD_NAME_MAX }>(name);
+        let res = unsafe { f(libc::pthread_self(), name.as_ptr()) };
+        debug_assert_eq!(res, 0);
+    }
+}
+
+#[cfg(target_os = "fuchsia")]
+pub fn set_name(name: &CStr) {
+    use crate::sys::pal::fuchsia::*;
+    unsafe {
+        zx_object_set_property(
+            zx_thread_self(),
+            ZX_PROP_NAME,
+            name.as_ptr() as *const libc::c_void,
+            name.to_bytes().len(),
+        );
+    }
+}
+
+#[cfg(target_os = "haiku")]
+pub fn set_name(name: &CStr) {
+    unsafe {
+        let thread_self = libc::find_thread(ptr::null_mut());
+        let res = libc::rename_thread(thread_self, name.as_ptr());
+        // We have no good way of propagating errors here, but in debug-builds let's check that this actually worked.
+        debug_assert_eq!(res, libc::B_OK);
+    }
+}
+
+#[cfg(target_os = "vxworks")]
+pub fn set_name(name: &CStr) {
+    let mut name = truncate_cstr::<{ (libc::VX_TASK_RENAME_LENGTH - 1) as usize }>(name);
+    let res = unsafe { libc::taskNameSet(libc::taskIdSelf(), name.as_mut_ptr()) };
+    debug_assert_eq!(res, libc::OK);
+}
+
+#[cfg(not(target_os = "espidf"))]
+pub fn sleep(dur: Duration) {
+    let mut secs = dur.as_secs();
+    let mut nsecs = dur.subsec_nanos() as _;
+
+    // If we're awoken with a signal then the return value will be -1 and
+    // nanosleep will fill in `ts` with the remaining time.
+    unsafe {
+        while secs > 0 || nsecs > 0 {
+            let mut ts = libc::timespec {
+                tv_sec: cmp::min(libc::time_t::MAX as u64, secs) as libc::time_t,
+                tv_nsec: nsecs,
+            };
+            secs -= ts.tv_sec as u64;
+            let ts_ptr = &raw mut ts;
+            if libc::nanosleep(ts_ptr, ts_ptr) == -1 {
+                assert_eq!(os::errno(), libc::EINTR);
+                secs += ts.tv_sec as u64;
+                nsecs = ts.tv_nsec;
+            } else {
+                nsecs = 0;
+            }
+        }
+    }
+}
+
+#[cfg(target_os = "espidf")]
+pub fn sleep(dur: Duration) {
+    // ESP-IDF does not have `nanosleep`, so we use `usleep` instead.
+    // As per the documentation of `usleep`, it is expected to support
+    // sleep times as big as at least up to 1 second.
+    //
+    // ESP-IDF does support almost up to `u32::MAX`, but due to a potential integer overflow in its
+    // `usleep` implementation
+    // (https://github.com/espressif/esp-idf/blob/d7ca8b94c852052e3bc33292287ef4dd62c9eeb1/components/newlib/time.c#L210),
+    // we limit the sleep time to the maximum one that would not cause the underlying `usleep` implementation to overflow
+    // (`portTICK_PERIOD_MS` can be anything between 1 to 1000, and is 10 by default).
+    const MAX_MICROS: u32 = u32::MAX - 1_000_000 - 1;
+
+    // Add any nanoseconds smaller than a microsecond as an extra microsecond
+    // so as to comply with the `std::thread::sleep` contract which mandates
+    // implementations to sleep for _at least_ the provided `dur`.
+    // We can't overflow `micros` as it is a `u128`, while `Duration` is a pair of
+    // (`u64` secs, `u32` nanos), where the nanos are strictly smaller than 1 second
+    // (i.e. < 1_000_000_000)
+    let mut micros = dur.as_micros() + if dur.subsec_nanos() % 1_000 > 0 { 1 } else { 0 };
+
+    while micros > 0 {
+        let st = if micros > MAX_MICROS as u128 { MAX_MICROS } else { micros as u32 };
+        unsafe {
+            libc::usleep(st);
+        }
+
+        micros -= st as u128;
+    }
+}
+
+// Any unix that has clock_nanosleep
+// If this list changes update the MIRI chock_nanosleep shim
+#[cfg(any(
+    target_os = "freebsd",
+    target_os = "netbsd",
+    target_os = "linux",
+    target_os = "android",
+    target_os = "solaris",
+    target_os = "illumos",
+    target_os = "dragonfly",
+    target_os = "hurd",
+    target_os = "fuchsia",
+    target_os = "vxworks",
+))]
+pub fn sleep_until(deadline: crate::time::Instant) {
+    use crate::time::Instant;
+
+    let Some(ts) = deadline.into_inner().into_timespec().to_timespec() else {
+        // The deadline is further in the future then can be passed to
+        // clock_nanosleep. We have to use Self::sleep instead. This might
+        // happen on 32 bit platforms, especially closer to 2038.
+        let now = Instant::now();
+        if let Some(delay) = deadline.checked_duration_since(now) {
+            sleep(delay);
+        }
+        return;
+    };
+
+    unsafe {
+        // When we get interrupted (res = EINTR) call clock_nanosleep again
+        loop {
+            let res = libc::clock_nanosleep(
+                crate::sys::time::Instant::CLOCK_ID,
+                libc::TIMER_ABSTIME,
+                &ts,
+                core::ptr::null_mut(), // not required with TIMER_ABSTIME
+            );
+
+            if res == 0 {
+                break;
+            } else {
+                assert_eq!(
+                    res,
+                    libc::EINTR,
+                    "timespec is in range,
+                         clockid is valid and kernel should support it"
+                );
+            }
+        }
+    }
+}
+
+pub fn yield_now() {
+    let ret = unsafe { libc::sched_yield() };
+    debug_assert_eq!(ret, 0);
+}
+
 #[cfg(any(target_os = "android", target_os = "linux"))]
 mod cgroups {
     //! Currently not covered
diff --git a/library/std/src/sys/pal/unsupported/thread.rs b/library/std/src/sys/thread/unsupported.rs
index 34d9b5ec70c..a5001efa3b4 100644
--- a/library/std/src/sys/pal/unsupported/thread.rs
+++ b/library/std/src/sys/thread/unsupported.rs
@@ -1,8 +1,7 @@
-use super::unsupported;
 use crate::ffi::CStr;
 use crate::io;
 use crate::num::NonZero;
-use crate::time::{Duration, Instant};
+use crate::time::Duration;
 
 pub struct Thread(!);
 
@@ -15,23 +14,7 @@ impl Thread {
         _name: Option<&str>,
         _p: Box<dyn FnOnce()>,
     ) -> io::Result<Thread> {
-        unsupported()
-    }
-
-    pub fn yield_now() {
-        // do nothing
-    }
-
-    pub fn set_name(_name: &CStr) {
-        // nope
-    }
-
-    pub fn sleep(_dur: Duration) {
-        panic!("can't sleep");
-    }
-
-    pub fn sleep_until(_deadline: Instant) {
-        panic!("can't sleep");
+        Err(io::Error::UNSUPPORTED_PLATFORM)
     }
 
     pub fn join(self) {
@@ -39,10 +22,22 @@ impl Thread {
     }
 }
 
-pub(crate) fn current_os_id() -> Option<u64> {
+pub fn available_parallelism() -> io::Result<NonZero<usize>> {
+    Err(io::Error::UNKNOWN_THREAD_COUNT)
+}
+
+pub fn current_os_id() -> Option<u64> {
     None
 }
 
-pub fn available_parallelism() -> io::Result<NonZero<usize>> {
-    unsupported()
+pub fn yield_now() {
+    // do nothing
+}
+
+pub fn set_name(_name: &CStr) {
+    // nope
+}
+
+pub fn sleep(_dur: Duration) {
+    panic!("can't sleep");
 }
diff --git a/library/std/src/sys/thread/vexos.rs b/library/std/src/sys/thread/vexos.rs
new file mode 100644
index 00000000000..d917dde4d0b
--- /dev/null
+++ b/library/std/src/sys/thread/vexos.rs
@@ -0,0 +1,17 @@
+use crate::time::{Duration, Instant};
+
+pub fn yield_now() {
+    unsafe {
+        vex_sdk::vexTasksRun();
+    }
+}
+
+pub fn sleep(dur: Duration) {
+    let start = Instant::now();
+
+    while start.elapsed() < dur {
+        unsafe {
+            vex_sdk::vexTasksRun();
+        }
+    }
+}
diff --git a/library/std/src/sys/thread/wasip1.rs b/library/std/src/sys/thread/wasip1.rs
new file mode 100644
index 00000000000..83001fad49c
--- /dev/null
+++ b/library/std/src/sys/thread/wasip1.rs
@@ -0,0 +1,185 @@
+#![forbid(unsafe_op_in_unsafe_fn)]
+
+#[cfg(target_feature = "atomics")]
+use crate::io;
+use crate::mem;
+#[cfg(target_feature = "atomics")]
+use crate::num::NonZero;
+#[cfg(target_feature = "atomics")]
+use crate::sys::os;
+use crate::time::Duration;
+#[cfg(target_feature = "atomics")]
+use crate::{cmp, ptr};
+
+// Add a few symbols not in upstream `libc` just yet.
+#[cfg(target_feature = "atomics")]
+mod libc {
+    pub use libc::*;
+
+    pub use crate::ffi;
+
+    // defined in wasi-libc
+    // https://github.com/WebAssembly/wasi-libc/blob/a6f871343313220b76009827ed0153586361c0d5/libc-top-half/musl/include/alltypes.h.in#L108
+    #[repr(C)]
+    union pthread_attr_union {
+        __i: [ffi::c_int; if size_of::<ffi::c_long>() == 8 { 14 } else { 9 }],
+        __vi: [ffi::c_int; if size_of::<ffi::c_long>() == 8 { 14 } else { 9 }],
+        __s: [ffi::c_ulong; if size_of::<ffi::c_long>() == 8 { 7 } else { 9 }],
+    }
+
+    #[repr(C)]
+    pub struct pthread_attr_t {
+        __u: pthread_attr_union,
+    }
+
+    #[allow(non_camel_case_types)]
+    pub type pthread_t = *mut ffi::c_void;
+
+    pub const _SC_NPROCESSORS_ONLN: ffi::c_int = 84;
+
+    unsafe extern "C" {
+        pub fn pthread_create(
+            native: *mut pthread_t,
+            attr: *const pthread_attr_t,
+            f: extern "C" fn(*mut ffi::c_void) -> *mut ffi::c_void,
+            value: *mut ffi::c_void,
+        ) -> ffi::c_int;
+        pub fn pthread_join(native: pthread_t, value: *mut *mut ffi::c_void) -> ffi::c_int;
+        pub fn pthread_attr_init(attrp: *mut pthread_attr_t) -> ffi::c_int;
+        pub fn pthread_attr_setstacksize(
+            attr: *mut pthread_attr_t,
+            stack_size: libc::size_t,
+        ) -> ffi::c_int;
+        pub fn pthread_attr_destroy(attr: *mut pthread_attr_t) -> ffi::c_int;
+        pub fn pthread_detach(thread: pthread_t) -> ffi::c_int;
+    }
+}
+
+#[cfg(target_feature = "atomics")]
+pub struct Thread {
+    id: libc::pthread_t,
+}
+
+#[cfg(target_feature = "atomics")]
+impl Drop for Thread {
+    fn drop(&mut self) {
+        let ret = unsafe { libc::pthread_detach(self.id) };
+        debug_assert_eq!(ret, 0);
+    }
+}
+
+pub const DEFAULT_MIN_STACK_SIZE: usize = 1024 * 1024;
+
+#[cfg(target_feature = "atomics")]
+impl Thread {
+    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
+    pub unsafe fn new(
+        stack: usize,
+        _name: Option<&str>,
+        p: Box<dyn FnOnce()>,
+    ) -> io::Result<Thread> {
+        let p = Box::into_raw(Box::new(p));
+        let mut native: libc::pthread_t = unsafe { mem::zeroed() };
+        let mut attr: libc::pthread_attr_t = unsafe { mem::zeroed() };
+        assert_eq!(unsafe { libc::pthread_attr_init(&mut attr) }, 0);
+
+        let stack_size = cmp::max(stack, DEFAULT_MIN_STACK_SIZE);
+
+        match unsafe { libc::pthread_attr_setstacksize(&mut attr, stack_size) } {
+            0 => {}
+            n => {
+                assert_eq!(n, libc::EINVAL);
+                // EINVAL means |stack_size| is either too small or not a
+                // multiple of the system page size. Because it's definitely
+                // >= PTHREAD_STACK_MIN, it must be an alignment issue.
+                // Round up to the nearest page and try again.
+                let page_size = os::page_size();
+                let stack_size =
+                    (stack_size + page_size - 1) & (-(page_size as isize - 1) as usize - 1);
+                assert_eq!(unsafe { libc::pthread_attr_setstacksize(&mut attr, stack_size) }, 0);
+            }
+        };
+
+        let ret = unsafe { libc::pthread_create(&mut native, &attr, thread_start, p as *mut _) };
+        // Note: if the thread creation fails and this assert fails, then p will
+        // be leaked. However, an alternative design could cause double-free
+        // which is clearly worse.
+        assert_eq!(unsafe { libc::pthread_attr_destroy(&mut attr) }, 0);
+
+        return if ret != 0 {
+            // The thread failed to start and as a result p was not consumed. Therefore, it is
+            // safe to reconstruct the box so that it gets deallocated.
+            unsafe {
+                drop(Box::from_raw(p));
+            }
+            Err(io::Error::from_raw_os_error(ret))
+        } else {
+            Ok(Thread { id: native })
+        };
+
+        extern "C" fn thread_start(main: *mut libc::c_void) -> *mut libc::c_void {
+            unsafe {
+                // Finally, let's run some code.
+                Box::from_raw(main as *mut Box<dyn FnOnce()>)();
+            }
+            ptr::null_mut()
+        }
+    }
+
+    pub fn join(self) {
+        let id = mem::ManuallyDrop::new(self).id;
+        let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
+        if ret != 0 {
+            rtabort!("failed to join thread: {}", io::Error::from_raw_os_error(ret));
+        }
+    }
+}
+
+#[cfg(target_feature = "atomics")]
+pub fn available_parallelism() -> io::Result<NonZero<usize>> {
+    match unsafe { libc::sysconf(libc::_SC_NPROCESSORS_ONLN) } {
+        -1 => Err(io::Error::last_os_error()),
+        cpus => NonZero::new(cpus as usize).ok_or(io::Error::UNKNOWN_THREAD_COUNT),
+    }
+}
+
+pub fn yield_now() {
+    let ret = unsafe { wasi::sched_yield() };
+    debug_assert_eq!(ret, Ok(()));
+}
+
+pub fn sleep(dur: Duration) {
+    let mut nanos = dur.as_nanos();
+    while nanos > 0 {
+        const USERDATA: wasi::Userdata = 0x0123_45678;
+
+        let clock = wasi::SubscriptionClock {
+            id: wasi::CLOCKID_MONOTONIC,
+            timeout: u64::try_from(nanos).unwrap_or(u64::MAX),
+            precision: 0,
+            flags: 0,
+        };
+        nanos -= u128::from(clock.timeout);
+
+        let in_ = wasi::Subscription {
+            userdata: USERDATA,
+            u: wasi::SubscriptionU { tag: 0, u: wasi::SubscriptionUU { clock } },
+        };
+        unsafe {
+            let mut event: wasi::Event = mem::zeroed();
+            let res = wasi::poll_oneoff(&in_, &mut event, 1);
+            match (res, event) {
+                (
+                    Ok(1),
+                    wasi::Event {
+                        userdata: USERDATA,
+                        error: wasi::ERRNO_SUCCESS,
+                        type_: wasi::EVENTTYPE_CLOCK,
+                        ..
+                    },
+                ) => {}
+                _ => panic!("thread::sleep(): unexpected result of poll_oneoff"),
+            }
+        }
+    }
+}
diff --git a/library/std/src/sys/thread/wasip2.rs b/library/std/src/sys/thread/wasip2.rs
new file mode 100644
index 00000000000..420cad2a5e4
--- /dev/null
+++ b/library/std/src/sys/thread/wasip2.rs
@@ -0,0 +1,32 @@
+use crate::time::{Duration, Instant};
+
+pub fn sleep(dur: Duration) {
+    // Sleep in increments of `u64::MAX` nanoseconds until the `dur` is
+    // entirely drained.
+    let mut remaining = dur.as_nanos();
+    while remaining > 0 {
+        let amt = u64::try_from(remaining).unwrap_or(u64::MAX);
+        wasip2::clocks::monotonic_clock::subscribe_duration(amt).block();
+        remaining -= u128::from(amt);
+    }
+}
+
+pub fn sleep_until(deadline: Instant) {
+    match u64::try_from(deadline.into_inner().as_duration().as_nanos()) {
+        // If the point in time we're sleeping to fits within a 64-bit
+        // number of nanoseconds then directly use `subscribe_instant`.
+        Ok(deadline) => {
+            wasip2::clocks::monotonic_clock::subscribe_instant(deadline).block();
+        }
+        // ... otherwise we're sleeping for 500+ years relative to the
+        // "start" of what the system is using as a clock so speed/accuracy
+        // is not so much of a concern. Use `sleep` instead.
+        Err(_) => {
+            let now = Instant::now();
+
+            if let Some(delay) = deadline.checked_duration_since(now) {
+                sleep(delay);
+            }
+        }
+    }
+}
diff --git a/library/std/src/sys/thread/wasm.rs b/library/std/src/sys/thread/wasm.rs
new file mode 100644
index 00000000000..e843bc992ba
--- /dev/null
+++ b/library/std/src/sys/thread/wasm.rs
@@ -0,0 +1,23 @@
+use crate::cmp;
+use crate::time::Duration;
+
+pub fn sleep(dur: Duration) {
+    #[cfg(target_arch = "wasm32")]
+    use core::arch::wasm32 as wasm;
+    #[cfg(target_arch = "wasm64")]
+    use core::arch::wasm64 as wasm;
+
+    // Use an atomic wait to block the current thread artificially with a
+    // timeout listed. Note that we should never be notified (return value
+    // of 0) or our comparison should never fail (return value of 1) so we
+    // should always only resume execution through a timeout (return value
+    // 2).
+    let mut nanos = dur.as_nanos();
+    while nanos > 0 {
+        let amt = cmp::min(i64::MAX as u128, nanos);
+        let mut x = 0;
+        let val = unsafe { wasm::memory_atomic_wait32(&mut x, 0, amt as i64) };
+        debug_assert_eq!(val, 2);
+        nanos -= amt;
+    }
+}
diff --git a/library/std/src/sys/pal/windows/thread.rs b/library/std/src/sys/thread/windows.rs
index b0e38220a2d..a5640c51c4a 100644
--- a/library/std/src/sys/pal/windows/thread.rs
+++ b/library/std/src/sys/thread/windows.rs
@@ -1,14 +1,14 @@
 use core::ffi::c_void;
 
-use super::time::WaitableTimer;
-use super::to_u16s;
 use crate::ffi::CStr;
 use crate::num::NonZero;
 use crate::os::windows::io::{AsRawHandle, HandleOrNull};
 use crate::sys::handle::Handle;
+use crate::sys::pal::time::WaitableTimer;
+use crate::sys::pal::{dur2timeout, to_u16s};
 use crate::sys::{c, stack_overflow};
 use crate::sys_common::FromInner;
-use crate::time::{Duration, Instant};
+use crate::time::Duration;
 use crate::{io, ptr};
 
 pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
@@ -62,24 +62,6 @@ impl Thread {
         }
     }
 
-    pub fn set_name(name: &CStr) {
-        if let Ok(utf8) = name.to_str() {
-            if let Ok(utf16) = to_u16s(utf8) {
-                unsafe {
-                    // SAFETY: the vec returned by `to_u16s` ends with a zero value
-                    Self::set_name_wide(&utf16)
-                }
-            };
-        };
-    }
-
-    /// # Safety
-    ///
-    /// `name` must end with a zero value
-    pub unsafe fn set_name_wide(name: &[u16]) {
-        unsafe { c::SetThreadDescription(c::GetCurrentThread(), name.as_ptr()) };
-    }
-
     pub fn join(self) {
         let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE) };
         if rc == c::WAIT_FAILED {
@@ -87,37 +69,6 @@ impl Thread {
         }
     }
 
-    pub fn yield_now() {
-        // This function will return 0 if there are no other threads to execute,
-        // but this also means that the yield was useless so this isn't really a
-        // case that needs to be worried about.
-        unsafe {
-            c::SwitchToThread();
-        }
-    }
-
-    pub fn sleep(dur: Duration) {
-        fn high_precision_sleep(dur: Duration) -> Result<(), ()> {
-            let timer = WaitableTimer::high_resolution()?;
-            timer.set(dur)?;
-            timer.wait()
-        }
-        // Attempt to use high-precision sleep (Windows 10, version 1803+).
-        // On error fallback to the standard `Sleep` function.
-        // Also preserves the zero duration behavior of `Sleep`.
-        if dur.is_zero() || high_precision_sleep(dur).is_err() {
-            unsafe { c::Sleep(super::dur2timeout(dur)) }
-        }
-    }
-
-    pub fn sleep_until(deadline: Instant) {
-        let now = Instant::now();
-
-        if let Some(delay) = deadline.checked_duration_since(now) {
-            Self::sleep(delay);
-        }
-    }
-
     pub fn handle(&self) -> &Handle {
         &self.handle
     }
@@ -127,14 +78,6 @@ impl Thread {
     }
 }
 
-pub(crate) fn current_os_id() -> Option<u64> {
-    // SAFETY: FFI call with no preconditions.
-    let id: u32 = unsafe { c::GetCurrentThreadId() };
-
-    // A return value of 0 indicates failed lookup.
-    if id == 0 { None } else { Some(id.into()) }
-}
-
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     let res = unsafe {
         let mut sysinfo: c::SYSTEM_INFO = crate::mem::zeroed();
@@ -146,3 +89,52 @@ pub fn available_parallelism() -> io::Result<NonZero<usize>> {
         cpus => Ok(unsafe { NonZero::new_unchecked(cpus) }),
     }
 }
+
+pub fn current_os_id() -> Option<u64> {
+    // SAFETY: FFI call with no preconditions.
+    let id: u32 = unsafe { c::GetCurrentThreadId() };
+
+    // A return value of 0 indicates failed lookup.
+    if id == 0 { None } else { Some(id.into()) }
+}
+
+pub fn set_name(name: &CStr) {
+    if let Ok(utf8) = name.to_str() {
+        if let Ok(utf16) = to_u16s(utf8) {
+            unsafe {
+                // SAFETY: the vec returned by `to_u16s` ends with a zero value
+                set_name_wide(&utf16)
+            }
+        };
+    };
+}
+
+/// # Safety
+///
+/// `name` must end with a zero value
+pub unsafe fn set_name_wide(name: &[u16]) {
+    unsafe { c::SetThreadDescription(c::GetCurrentThread(), name.as_ptr()) };
+}
+
+pub fn sleep(dur: Duration) {
+    fn high_precision_sleep(dur: Duration) -> Result<(), ()> {
+        let timer = WaitableTimer::high_resolution()?;
+        timer.set(dur)?;
+        timer.wait()
+    }
+    // Attempt to use high-precision sleep (Windows 10, version 1803+).
+    // On error fallback to the standard `Sleep` function.
+    // Also preserves the zero duration behavior of `Sleep`.
+    if dur.is_zero() || high_precision_sleep(dur).is_err() {
+        unsafe { c::Sleep(dur2timeout(dur)) }
+    }
+}
+
+pub fn yield_now() {
+    // This function will return 0 if there are no other threads to execute,
+    // but this also means that the yield was useless so this isn't really a
+    // case that needs to be worried about.
+    unsafe {
+        c::SwitchToThread();
+    }
+}
diff --git a/library/std/src/sys/pal/xous/thread.rs b/library/std/src/sys/thread/xous.rs
index 92803c94c6e..133e15a0928 100644
--- a/library/std/src/sys/pal/xous/thread.rs
+++ b/library/std/src/sys/thread/xous.rs
@@ -1,6 +1,5 @@
 use core::arch::asm;
 
-use crate::ffi::CStr;
 use crate::io;
 use crate::num::NonZero;
 use crate::os::xous::ffi::{
@@ -8,7 +7,7 @@ use crate::os::xous::ffi::{
     map_memory, update_memory_flags,
 };
 use crate::os::xous::services::{TicktimerScalar, ticktimer_server};
-use crate::time::{Duration, Instant};
+use crate::time::Duration;
 
 pub struct Thread {
     tid: ThreadId,
@@ -110,46 +109,29 @@ impl Thread {
         Ok(Thread { tid })
     }
 
-    pub fn yield_now() {
-        do_yield();
-    }
-
-    pub fn set_name(_name: &CStr) {
-        // nope
-    }
-
-    pub fn sleep(dur: Duration) {
-        // Because the sleep server works on units of `usized milliseconds`, split
-        // the messages up into these chunks. This means we may run into issues
-        // if you try to sleep a thread for more than 49 days on a 32-bit system.
-        let mut millis = dur.as_millis();
-        while millis > 0 {
-            let sleep_duration =
-                if millis > (usize::MAX as _) { usize::MAX } else { millis as usize };
-            blocking_scalar(ticktimer_server(), TicktimerScalar::SleepMs(sleep_duration).into())
-                .expect("failed to send message to ticktimer server");
-            millis -= sleep_duration as u128;
-        }
-    }
-
-    pub fn sleep_until(deadline: Instant) {
-        let now = Instant::now();
-
-        if let Some(delay) = deadline.checked_duration_since(now) {
-            Self::sleep(delay);
-        }
-    }
-
     pub fn join(self) {
         join_thread(self.tid).unwrap();
     }
 }
 
-pub(crate) fn current_os_id() -> Option<u64> {
-    None
-}
-
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     // We're unicore right now.
     Ok(unsafe { NonZero::new_unchecked(1) })
 }
+
+pub fn yield_now() {
+    do_yield();
+}
+
+pub fn sleep(dur: Duration) {
+    // Because the sleep server works on units of `usized milliseconds`, split
+    // the messages up into these chunks. This means we may run into issues
+    // if you try to sleep a thread for more than 49 days on a 32-bit system.
+    let mut millis = dur.as_millis();
+    while millis > 0 {
+        let sleep_duration = if millis > (usize::MAX as _) { usize::MAX } else { millis as usize };
+        blocking_scalar(ticktimer_server(), TicktimerScalar::SleepMs(sleep_duration).into())
+            .expect("failed to send message to ticktimer server");
+        millis -= sleep_duration as u128;
+    }
+}
diff --git a/library/std/src/sys/thread_local/mod.rs b/library/std/src/sys/thread_local/mod.rs
index cff74857c47..f7f051b1add 100644
--- a/library/std/src/sys/thread_local/mod.rs
+++ b/library/std/src/sys/thread_local/mod.rs
@@ -29,6 +29,7 @@ cfg_select! {
         target_os = "uefi",
         target_os = "zkvm",
         target_os = "trusty",
+        target_os = "vexos",
     ) => {
         mod no_threads;
         pub use no_threads::{EagerStorage, LazyStorage, thread_local_inner};
@@ -41,7 +42,7 @@ cfg_select! {
     }
     _ => {
         mod os;
-        pub use os::{Storage, thread_local_inner};
+        pub use os::{Storage, thread_local_inner, value_align};
         pub(crate) use os::{LocalPointer, local_pointer};
     }
 }
@@ -98,6 +99,7 @@ pub(crate) mod guard {
             target_os = "uefi",
             target_os = "zkvm",
             target_os = "trusty",
+            target_os = "vexos",
         ) => {
             pub(crate) fn enable() {
                 // FIXME: Right now there is no concept of "thread exit" on
diff --git a/library/std/src/sys/thread_local/native/eager.rs b/library/std/src/sys/thread_local/native/eager.rs
index fd48c4f7202..23abad645c1 100644
--- a/library/std/src/sys/thread_local/native/eager.rs
+++ b/library/std/src/sys/thread_local/native/eager.rs
@@ -10,9 +10,11 @@ enum State {
 }
 
 #[allow(missing_debug_implementations)]
+#[repr(C)]
 pub struct Storage<T> {
-    state: Cell<State>,
+    // This field must be first, for correctness of `#[rustc_align_static]`
     val: UnsafeCell<T>,
+    state: Cell<State>,
 }
 
 impl<T> Storage<T> {
diff --git a/library/std/src/sys/thread_local/native/lazy.rs b/library/std/src/sys/thread_local/native/lazy.rs
index b556dd9aa25..02939a74fc0 100644
--- a/library/std/src/sys/thread_local/native/lazy.rs
+++ b/library/std/src/sys/thread_local/native/lazy.rs
@@ -27,9 +27,11 @@ enum State<D> {
 }
 
 #[allow(missing_debug_implementations)]
+#[repr(C)]
 pub struct Storage<T, D> {
-    state: Cell<State<D>>,
+    // This field must be first, for correctness of `#[rustc_align_static]`
     value: UnsafeCell<MaybeUninit<T>>,
+    state: Cell<State<D>>,
 }
 
 impl<T, D> Storage<T, D>
diff --git a/library/std/src/sys/thread_local/native/mod.rs b/library/std/src/sys/thread_local/native/mod.rs
index a5dffe3c458..5dc14240804 100644
--- a/library/std/src/sys/thread_local/native/mod.rs
+++ b/library/std/src/sys/thread_local/native/mod.rs
@@ -54,7 +54,7 @@ pub macro thread_local_inner {
     // test in `tests/thread.rs` if these types are renamed.
 
     // Used to generate the `LocalKey` value for const-initialized thread locals.
-    (@key $t:ty, const $init:expr) => {{
+    (@key $t:ty, $(#[$align_attr:meta])*, const $init:expr) => {{
         const __INIT: $t = $init;
 
         unsafe {
@@ -62,6 +62,7 @@ pub macro thread_local_inner {
                 if $crate::mem::needs_drop::<$t>() {
                     |_| {
                         #[thread_local]
+                        $(#[$align_attr])*
                         static VAL: $crate::thread::local_impl::EagerStorage<$t>
                             = $crate::thread::local_impl::EagerStorage::new(__INIT);
                         VAL.get()
@@ -69,6 +70,7 @@ pub macro thread_local_inner {
                 } else {
                     |_| {
                         #[thread_local]
+                        $(#[$align_attr])*
                         static VAL: $t = __INIT;
                         &VAL
                     }
@@ -78,7 +80,7 @@ pub macro thread_local_inner {
     }},
 
     // used to generate the `LocalKey` value for `thread_local!`
-    (@key $t:ty, $init:expr) => {{
+    (@key $t:ty, $(#[$align_attr:meta])*, $init:expr) => {{
         #[inline]
         fn __init() -> $t {
             $init
@@ -89,6 +91,7 @@ pub macro thread_local_inner {
                 if $crate::mem::needs_drop::<$t>() {
                     |init| {
                         #[thread_local]
+                        $(#[$align_attr])*
                         static VAL: $crate::thread::local_impl::LazyStorage<$t, ()>
                             = $crate::thread::local_impl::LazyStorage::new();
                         VAL.get_or_init(init, __init)
@@ -96,6 +99,7 @@ pub macro thread_local_inner {
                 } else {
                     |init| {
                         #[thread_local]
+                        $(#[$align_attr])*
                         static VAL: $crate::thread::local_impl::LazyStorage<$t, !>
                             = $crate::thread::local_impl::LazyStorage::new();
                         VAL.get_or_init(init, __init)
@@ -104,10 +108,6 @@ pub macro thread_local_inner {
             })
         }
     }},
-    ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $($init:tt)*) => {
-        $(#[$attr])* $vis const $name: $crate::thread::LocalKey<$t> =
-            $crate::thread::local_impl::thread_local_inner!(@key $t, $($init)*);
-    },
 }
 
 #[rustc_macro_transparency = "semitransparent"]
diff --git a/library/std/src/sys/thread_local/no_threads.rs b/library/std/src/sys/thread_local/no_threads.rs
index 4da01a84acf..409dfb19518 100644
--- a/library/std/src/sys/thread_local/no_threads.rs
+++ b/library/std/src/sys/thread_local/no_threads.rs
@@ -2,6 +2,7 @@
 //! thread locals and we can instead just use plain statics!
 
 use crate::cell::{Cell, UnsafeCell};
+use crate::mem::MaybeUninit;
 use crate::ptr;
 
 #[doc(hidden)]
@@ -11,12 +12,13 @@ use crate::ptr;
 #[rustc_macro_transparency = "semitransparent"]
 pub macro thread_local_inner {
     // used to generate the `LocalKey` value for const-initialized thread locals
-    (@key $t:ty, const $init:expr) => {{
+    (@key $t:ty, $(#[$align_attr:meta])*, const $init:expr) => {{
         const __INIT: $t = $init;
 
         // NOTE: Please update the shadowing test in `tests/thread.rs` if these types are renamed.
         unsafe {
             $crate::thread::LocalKey::new(|_| {
+                $(#[$align_attr])*
                 static VAL: $crate::thread::local_impl::EagerStorage<$t> =
                     $crate::thread::local_impl::EagerStorage { value: __INIT };
                 &VAL.value
@@ -25,27 +27,22 @@ pub macro thread_local_inner {
     }},
 
     // used to generate the `LocalKey` value for `thread_local!`
-    (@key $t:ty, $init:expr) => {{
+    (@key $t:ty, $(#[$align_attr:meta])*, $init:expr) => {{
         #[inline]
         fn __init() -> $t { $init }
 
         unsafe {
-            use $crate::thread::LocalKey;
-            use $crate::thread::local_impl::LazyStorage;
-
-            LocalKey::new(|init| {
-                static VAL: LazyStorage<$t> = LazyStorage::new();
+            $crate::thread::LocalKey::new(|init| {
+                $(#[$align_attr])*
+                static VAL: $crate::thread::local_impl::LazyStorage<$t> = $crate::thread::local_impl::LazyStorage::new();
                 VAL.get(init, __init)
             })
         }
     }},
-    ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $($init:tt)*) => {
-        $(#[$attr])* $vis const $name: $crate::thread::LocalKey<$t> =
-            $crate::thread::local_impl::thread_local_inner!(@key $t, $($init)*);
-    },
 }
 
 #[allow(missing_debug_implementations)]
+#[repr(transparent)] // Required for correctness of `#[rustc_align_static]`
 pub struct EagerStorage<T> {
     pub value: T,
 }
@@ -53,14 +50,27 @@ pub struct EagerStorage<T> {
 // SAFETY: the target doesn't have threads.
 unsafe impl<T> Sync for EagerStorage<T> {}
 
+#[derive(Clone, Copy, PartialEq, Eq)]
+enum State {
+    Initial,
+    Alive,
+    Destroying,
+}
+
 #[allow(missing_debug_implementations)]
+#[repr(C)]
 pub struct LazyStorage<T> {
-    value: UnsafeCell<Option<T>>,
+    // This field must be first, for correctness of `#[rustc_align_static]`
+    value: UnsafeCell<MaybeUninit<T>>,
+    state: Cell<State>,
 }
 
 impl<T> LazyStorage<T> {
     pub const fn new() -> LazyStorage<T> {
-        LazyStorage { value: UnsafeCell::new(None) }
+        LazyStorage {
+            value: UnsafeCell::new(MaybeUninit::uninit()),
+            state: Cell::new(State::Initial),
+        }
     }
 
     /// Gets a pointer to the TLS value, potentially initializing it with the
@@ -70,24 +80,39 @@ impl<T> LazyStorage<T> {
     /// has occurred.
     #[inline]
     pub fn get(&'static self, i: Option<&mut Option<T>>, f: impl FnOnce() -> T) -> *const T {
-        let value = unsafe { &*self.value.get() };
-        match value {
-            Some(v) => v,
-            None => self.initialize(i, f),
+        if self.state.get() == State::Alive {
+            self.value.get() as *const T
+        } else {
+            self.initialize(i, f)
         }
     }
 
     #[cold]
     fn initialize(&'static self, i: Option<&mut Option<T>>, f: impl FnOnce() -> T) -> *const T {
         let value = i.and_then(Option::take).unwrap_or_else(f);
-        // Destroy the old value, after updating the TLS variable as the
-        // destructor might reference it.
+
+        // Destroy the old value if it is initialized
         // FIXME(#110897): maybe panic on recursive initialization.
+        if self.state.get() == State::Alive {
+            self.state.set(State::Destroying);
+            // Safety: we check for no initialization during drop below
+            unsafe {
+                ptr::drop_in_place(self.value.get() as *mut T);
+            }
+            self.state.set(State::Initial);
+        }
+
+        // Guard against initialization during drop
+        if self.state.get() == State::Destroying {
+            panic!("Attempted to initialize thread-local while it is being dropped");
+        }
+
         unsafe {
-            self.value.get().replace(Some(value));
+            self.value.get().write(MaybeUninit::new(value));
         }
-        // SAFETY: we just set this to `Some`.
-        unsafe { (*self.value.get()).as_ref().unwrap_unchecked() }
+        self.state.set(State::Alive);
+
+        self.value.get() as *const T
     }
 }
 
diff --git a/library/std/src/sys/thread_local/os.rs b/library/std/src/sys/thread_local/os.rs
index fe6af27db3a..88bb5ae7c65 100644
--- a/library/std/src/sys/thread_local/os.rs
+++ b/library/std/src/sys/thread_local/os.rs
@@ -1,8 +1,12 @@
 use super::key::{Key, LazyKey, get, set};
 use super::{abort_on_dtor_unwind, guard};
+use crate::alloc::{self, Layout};
 use crate::cell::Cell;
 use crate::marker::PhantomData;
-use crate::ptr;
+use crate::mem::ManuallyDrop;
+use crate::ops::Deref;
+use crate::panic::{AssertUnwindSafe, catch_unwind, resume_unwind};
+use crate::ptr::{self, NonNull};
 
 #[doc(hidden)]
 #[allow_internal_unstable(thread_local_internals)]
@@ -10,17 +14,12 @@ use crate::ptr;
 #[unstable(feature = "thread_local_internals", issue = "none")]
 #[rustc_macro_transparency = "semitransparent"]
 pub macro thread_local_inner {
-    // used to generate the `LocalKey` value for const-initialized thread locals
-    (@key $t:ty, const $init:expr) => {
-        $crate::thread::local_impl::thread_local_inner!(@key $t, { const INIT_EXPR: $t = $init; INIT_EXPR })
-    },
-
     // NOTE: we cannot import `Storage` or `LocalKey` with a `use` because that can shadow user
     // provided type or type alias with a matching name. Please update the shadowing test in
     // `tests/thread.rs` if these types are renamed.
 
     // used to generate the `LocalKey` value for `thread_local!`.
-    (@key $t:ty, $init:expr) => {{
+    (@key $t:ty, $($(#[$($align_attr:tt)*])+)?, $init:expr) => {{
         #[inline]
         fn __init() -> $t { $init }
 
@@ -29,37 +28,148 @@ pub macro thread_local_inner {
         // in `tests/thread.rs` if these types are renamed.
         unsafe {
             $crate::thread::LocalKey::new(|init| {
-                static VAL: $crate::thread::local_impl::Storage<$t>
+                static VAL: $crate::thread::local_impl::Storage<$t, {
+                    $({
+                        // Ensure that attributes have valid syntax
+                        // and that the proper feature gate is enabled
+                        $(#[$($align_attr)*])+
+                        #[allow(unused)]
+                        static DUMMY: () = ();
+                    })?
+
+                    #[allow(unused_mut)]
+                    let mut final_align = $crate::thread::local_impl::value_align::<$t>();
+                    $($($crate::thread::local_impl::thread_local_inner!(@align final_align, $($align_attr)*);)+)?
+                    final_align
+                }>
                     = $crate::thread::local_impl::Storage::new();
                 VAL.get(init, __init)
             })
         }
     }},
-    ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $($init:tt)*) => {
-        $(#[$attr])* $vis const $name: $crate::thread::LocalKey<$t> =
-            $crate::thread::local_impl::thread_local_inner!(@key $t, $($init)*);
+
+    // process a single `rustc_align_static` attribute
+    (@align $final_align:ident, rustc_align_static($($align:tt)*) $(, $($attr_rest:tt)+)?) => {
+        let new_align: $crate::primitive::usize = $($align)*;
+        if new_align > $final_align {
+            $final_align = new_align;
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
+    },
+
+    // process a single `cfg_attr` attribute
+    // by translating it into a `cfg`ed block and recursing.
+    // https://doc.rust-lang.org/reference/conditional-compilation.html#railroad-ConfigurationPredicate
+
+    (@align $final_align:ident, cfg_attr(true, $($cfg_rhs:tt)*) $(, $($attr_rest:tt)+)?) => {
+        #[cfg(true)]
+        {
+            $crate::thread::local_impl::thread_local_inner!(@align $final_align, $($cfg_rhs)*);
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
+    },
+
+    (@align $final_align:ident, cfg_attr(false, $($cfg_rhs:tt)*) $(, $($attr_rest:tt)+)?) => {
+        #[cfg(false)]
+        {
+            $crate::thread::local_impl::thread_local_inner!(@align $final_align, $($cfg_rhs)*);
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
+    },
+
+    (@align $final_align:ident, cfg_attr($cfg_pred:meta, $($cfg_rhs:tt)*) $(, $($attr_rest:tt)+)?) => {
+        #[cfg($cfg_pred)]
+        {
+            $crate::thread::local_impl::thread_local_inner!(@align $final_align, $($cfg_rhs)*);
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
     },
 }
 
 /// Use a regular global static to store this key; the state provided will then be
 /// thread-local.
+/// INVARIANT: ALIGN must be a valid alignment, and no less than `value_align::<T>`.
 #[allow(missing_debug_implementations)]
-pub struct Storage<T> {
+pub struct Storage<T, const ALIGN: usize> {
     key: LazyKey,
     marker: PhantomData<Cell<T>>,
 }
 
-unsafe impl<T> Sync for Storage<T> {}
+unsafe impl<T, const ALIGN: usize> Sync for Storage<T, ALIGN> {}
 
+#[repr(C)]
 struct Value<T: 'static> {
+    // This field must be first, for correctness of `#[rustc_align_static]`
     value: T,
     // INVARIANT: if this value is stored under a TLS key, `key` must be that `key`.
     key: Key,
 }
 
-impl<T: 'static> Storage<T> {
-    pub const fn new() -> Storage<T> {
-        Storage { key: LazyKey::new(Some(destroy_value::<T>)), marker: PhantomData }
+pub const fn value_align<T: 'static>() -> usize {
+    crate::mem::align_of::<Value<T>>()
+}
+
+/// Equivalent to `Box<Value<T>>`, but potentially over-aligned.
+struct AlignedBox<T: 'static, const ALIGN: usize> {
+    ptr: NonNull<Value<T>>,
+}
+
+impl<T: 'static, const ALIGN: usize> AlignedBox<T, ALIGN> {
+    #[inline]
+    fn new(v: Value<T>) -> Self {
+        let layout = Layout::new::<Value<T>>().align_to(ALIGN).unwrap();
+
+        let ptr: *mut Value<T> = (unsafe { alloc::alloc(layout) }).cast();
+        let Some(ptr) = NonNull::new(ptr) else {
+            alloc::handle_alloc_error(layout);
+        };
+        unsafe { ptr.write(v) };
+        Self { ptr }
+    }
+
+    #[inline]
+    fn into_raw(b: Self) -> *mut Value<T> {
+        let md = ManuallyDrop::new(b);
+        md.ptr.as_ptr()
+    }
+
+    #[inline]
+    unsafe fn from_raw(ptr: *mut Value<T>) -> Self {
+        Self { ptr: unsafe { NonNull::new_unchecked(ptr) } }
+    }
+}
+
+impl<T: 'static, const ALIGN: usize> Deref for AlignedBox<T, ALIGN> {
+    type Target = Value<T>;
+
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        unsafe { &*(self.ptr.as_ptr()) }
+    }
+}
+
+impl<T: 'static, const ALIGN: usize> Drop for AlignedBox<T, ALIGN> {
+    #[inline]
+    fn drop(&mut self) {
+        let layout = Layout::new::<Value<T>>().align_to(ALIGN).unwrap();
+
+        unsafe {
+            let unwind_result = catch_unwind(AssertUnwindSafe(|| self.ptr.drop_in_place()));
+            alloc::dealloc(self.ptr.as_ptr().cast(), layout);
+            if let Err(payload) = unwind_result {
+                resume_unwind(payload);
+            }
+        }
+    }
+}
+
+impl<T: 'static, const ALIGN: usize> Storage<T, ALIGN> {
+    pub const fn new() -> Storage<T, ALIGN> {
+        Storage { key: LazyKey::new(Some(destroy_value::<T, ALIGN>)), marker: PhantomData }
     }
 
     /// Gets a pointer to the TLS value, potentially initializing it with the
@@ -95,8 +205,11 @@ impl<T: 'static> Storage<T> {
             return ptr::null();
         }
 
-        let value = Box::new(Value { value: i.and_then(Option::take).unwrap_or_else(f), key });
-        let ptr = Box::into_raw(value);
+        let value = AlignedBox::<T, ALIGN>::new(Value {
+            value: i.and_then(Option::take).unwrap_or_else(f),
+            key,
+        });
+        let ptr = AlignedBox::into_raw(value);
 
         // SAFETY:
         // * key came from a `LazyKey` and is thus correct.
@@ -114,7 +227,7 @@ impl<T: 'static> Storage<T> {
             // initializer has already returned and the next scope only starts
             // after we return the pointer. Therefore, there can be no references
             // to the old value.
-            drop(unsafe { Box::from_raw(old) });
+            drop(unsafe { AlignedBox::<T, ALIGN>::from_raw(old) });
         }
 
         // SAFETY: We just created this value above.
@@ -122,7 +235,7 @@ impl<T: 'static> Storage<T> {
     }
 }
 
-unsafe extern "C" fn destroy_value<T: 'static>(ptr: *mut u8) {
+unsafe extern "C" fn destroy_value<T: 'static, const ALIGN: usize>(ptr: *mut u8) {
     // SAFETY:
     //
     // The OS TLS ensures that this key contains a null value when this
@@ -133,7 +246,7 @@ unsafe extern "C" fn destroy_value<T: 'static>(ptr: *mut u8) {
     // Note that to prevent an infinite loop we reset it back to null right
     // before we return from the destructor ourselves.
     abort_on_dtor_unwind(|| {
-        let ptr = unsafe { Box::from_raw(ptr as *mut Value<T>) };
+        let ptr = unsafe { AlignedBox::<T, ALIGN>::from_raw(ptr as *mut Value<T>) };
         let key = ptr.key;
         // SAFETY: `key` is the TLS key `ptr` was stored under.
         unsafe { set(key, ptr::without_provenance_mut(1)) };
diff --git a/library/std/src/thread/current.rs b/library/std/src/thread/current.rs
index 7da1621da45..f00212bfcb6 100644
--- a/library/std/src/thread/current.rs
+++ b/library/std/src/thread/current.rs
@@ -133,12 +133,32 @@ pub(super) fn set_current(thread: Thread) -> Result<(), Thread> {
     Ok(())
 }
 
-/// Gets the id of the thread that invokes it.
+/// Gets the unique identifier of the thread which invokes it.
+///
+/// Calling this function may be more efficient than accessing the current
+/// thread id through the current thread handle. i.e. `thread::current().id()`.
 ///
 /// This function will always succeed, will always return the same value for
 /// one thread and is guaranteed not to call the global allocator.
+///
+/// # Examples
+///
+/// ```
+/// #![feature(current_thread_id)]
+///
+/// use std::thread;
+///
+/// let other_thread = thread::spawn(|| {
+///     thread::current_id()
+/// });
+///
+/// let other_thread_id = other_thread.join().unwrap();
+/// assert_ne!(thread::current_id(), other_thread_id);
+/// ```
 #[inline]
-pub(crate) fn current_id() -> ThreadId {
+#[must_use]
+#[unstable(feature = "current_thread_id", issue = "147194")]
+pub fn current_id() -> ThreadId {
     // If accessing the persistent thread ID takes multiple TLS accesses, try
     // to retrieve it from the current thread handle, which will only take one
     // TLS access.
diff --git a/library/std/src/thread/local.rs b/library/std/src/thread/local.rs
index 797feeb2bbb..4259a4d1f3b 100644
--- a/library/std/src/thread/local.rs
+++ b/library/std/src/thread/local.rs
@@ -132,6 +132,216 @@ impl<T: 'static> fmt::Debug for LocalKey<T> {
     }
 }
 
+#[doc(hidden)]
+#[allow_internal_unstable(thread_local_internals)]
+#[unstable(feature = "thread_local_internals", issue = "none")]
+#[rustc_macro_transparency = "semitransparent"]
+pub macro thread_local_process_attrs {
+
+    // Parse `cfg_attr` to figure out whether it's a `rustc_align_static`.
+    // Each `cfg_attr` can have zero or more attributes on the RHS, and can be nested.
+
+    // finished parsing the `cfg_attr`, it had no `rustc_align_static`
+    (
+        [] [$(#[$($prev_other_attrs:tt)*])*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [] };
+        [$($prev_align_attrs_ret:tt)*] [$($prev_other_attrs_ret:tt)*];
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs_ret)*] [$($prev_other_attrs_ret)* #[cfg_attr($($predicate)*, $($($prev_other_attrs)*),*)]];
+            $($rest)*
+        );
+    ),
+
+    // finished parsing the `cfg_attr`, it had nothing but `rustc_align_static`
+    (
+        [$(#[$($prev_align_attrs:tt)*])+] [];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [] };
+        [$($prev_align_attrs_ret:tt)*] [$($prev_other_attrs_ret:tt)*];
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs_ret)*  #[cfg_attr($($predicate)*, $($($prev_align_attrs)*),+)]] [$($prev_other_attrs_ret)*];
+            $($rest)*
+        );
+    ),
+
+    // finished parsing the `cfg_attr`, it had a mix of `rustc_align_static` and other attrs
+    (
+        [$(#[$($prev_align_attrs:tt)*])+] [$(#[$($prev_other_attrs:tt)*])+];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [] };
+        [$($prev_align_attrs_ret:tt)*] [$($prev_other_attrs_ret:tt)*];
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs_ret)*  #[cfg_attr($($predicate)*, $($($prev_align_attrs)*),+)]] [$($prev_other_attrs_ret)* #[cfg_attr($($predicate)*, $($($prev_other_attrs)*),+)]];
+            $($rest)*
+        );
+    ),
+
+    // it's a `rustc_align_static`
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [rustc_align_static($($align_static_args:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)* #[rustc_align_static($($align_static_args)*)]] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+    // it's a nested `cfg_attr(true, ...)`; recurse into RHS
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [cfg_attr(true, $($cfg_rhs:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (true), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+    // it's a nested `cfg_attr(false, ...)`; recurse into RHS
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [cfg_attr(false, $($cfg_rhs:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (false), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+
+    // it's a nested `cfg_attr(..., ...)`; recurse into RHS
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [cfg_attr($cfg_lhs:meta, $($cfg_rhs:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: ($cfg_lhs), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+    // it's some other attribute
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [$meta:meta $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)* #[$meta]];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+
+    // Separate attributes into `rustc_align_static` and everything else:
+
+    // `rustc_align_static` attribute
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[rustc_align_static $($attr_rest:tt)*] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)* #[rustc_align_static $($attr_rest)*]] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // `cfg_attr(true, ...)` attribute; parse it
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[cfg_attr(true, $($cfg_rhs:tt)*)] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (true), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // `cfg_attr(false, ...)` attribute; parse it
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[cfg_attr(false, $($cfg_rhs:tt)*)] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (false), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // `cfg_attr(..., ...)` attribute; parse it
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[cfg_attr($cfg_pred:meta, $($cfg_rhs:tt)*)] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: ($cfg_pred), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // doc comment not followed by any other attributes; process it all at once to avoid blowing recursion limit
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; $(#[doc $($doc_rhs:tt)*])+ $vis:vis static $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)* $(#[doc $($doc_rhs)*])+];
+            $vis static $($rest)*
+        );
+    ),
+
+    // 8 lines of doc comment; process them all at once to avoid blowing recursion limit
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+     #[doc $($doc_rhs_1:tt)*] #[doc $($doc_rhs_2:tt)*] #[doc $($doc_rhs_3:tt)*] #[doc $($doc_rhs_4:tt)*]
+     #[doc $($doc_rhs_5:tt)*] #[doc $($doc_rhs_6:tt)*] #[doc $($doc_rhs_7:tt)*] #[doc $($doc_rhs_8:tt)*]
+     $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*
+            #[doc $($doc_rhs_1)*] #[doc $($doc_rhs_2)*] #[doc $($doc_rhs_3)*] #[doc $($doc_rhs_4)*]
+            #[doc $($doc_rhs_5)*] #[doc $($doc_rhs_6)*] #[doc $($doc_rhs_7)*] #[doc $($doc_rhs_8)*]];
+            $($rest)*
+        );
+    ),
+
+    // other attribute
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[$($attr:tt)*] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)* #[$($attr)*]];
+            $($rest)*
+        );
+    ),
+
+
+    // Delegate to `thread_local_inner` once attributes are fully categorized:
+
+    // process `const` declaration and recurse
+    ([$($align_attrs:tt)*] [$($other_attrs:tt)*]; $vis:vis static $name:ident: $t:ty = const $init:block $(; $($($rest:tt)+)?)?) => (
+        $($other_attrs)* $vis const $name: $crate::thread::LocalKey<$t> =
+            $crate::thread::local_impl::thread_local_inner!(@key $t, $($align_attrs)*, const $init);
+
+        $($($crate::thread::local_impl::thread_local_process_attrs!([] []; $($rest)+);)?)?
+    ),
+
+    // process non-`const` declaration and recurse
+    ([$($align_attrs:tt)*] [$($other_attrs:tt)*]; $vis:vis static $name:ident: $t:ty = $init:expr $(; $($($rest:tt)+)?)?) => (
+        $($other_attrs)* $vis const $name: $crate::thread::LocalKey<$t> =
+            $crate::thread::local_impl::thread_local_inner!(@key $t, $($align_attrs)*, $init);
+
+        $($($crate::thread::local_impl::thread_local_process_attrs!([] []; $($rest)+);)?)?
+    ),
+}
+
 /// Declare a new thread local storage key of type [`std::thread::LocalKey`].
 ///
 /// # Syntax
@@ -182,28 +392,11 @@ impl<T: 'static> fmt::Debug for LocalKey<T> {
 #[cfg_attr(not(test), rustc_diagnostic_item = "thread_local_macro")]
 #[allow_internal_unstable(thread_local_internals)]
 macro_rules! thread_local {
-    // empty (base case for the recursion)
     () => {};
 
-    ($(#[$attr:meta])* $vis:vis static $name:ident: $t:ty = const $init:block; $($rest:tt)*) => (
-        $crate::thread::local_impl::thread_local_inner!($(#[$attr])* $vis $name, $t, const $init);
-        $crate::thread_local!($($rest)*);
-    );
-
-    ($(#[$attr:meta])* $vis:vis static $name:ident: $t:ty = const $init:block) => (
-        $crate::thread::local_impl::thread_local_inner!($(#[$attr])* $vis $name, $t, const $init);
-    );
-
-    // process multiple declarations
-    ($(#[$attr:meta])* $vis:vis static $name:ident: $t:ty = $init:expr; $($rest:tt)*) => (
-        $crate::thread::local_impl::thread_local_inner!($(#[$attr])* $vis $name, $t, $init);
-        $crate::thread_local!($($rest)*);
-    );
-
-    // handle a single declaration
-    ($(#[$attr:meta])* $vis:vis static $name:ident: $t:ty = $init:expr) => (
-        $crate::thread::local_impl::thread_local_inner!($(#[$attr])* $vis $name, $t, $init);
-    );
+    ($($tt:tt)+) => {
+        $crate::thread::local_impl::thread_local_process_attrs!([] []; $($tt)+);
+    };
 }
 
 /// An error returned by [`LocalKey::try_with`](struct.LocalKey.html#method.try_with).
@@ -230,7 +423,7 @@ impl fmt::Display for AccessError {
 impl Error for AccessError {}
 
 // This ensures the panicking code is outlined from `with` for `LocalKey`.
-#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
+#[cfg_attr(not(panic = "immediate-abort"), inline(never))]
 #[track_caller]
 #[cold]
 fn panic_access_error(err: AccessError) -> ! {
diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs
index b6059c28cec..fd7cce3f97d 100644
--- a/library/std/src/thread/mod.rs
+++ b/library/std/src/thread/mod.rs
@@ -183,7 +183,9 @@ mod current;
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use current::current;
-pub(crate) use current::{current_id, current_or_unnamed, current_os_id, drop_current};
+#[unstable(feature = "current_thread_id", issue = "147194")]
+pub use current::current_id;
+pub(crate) use current::{current_or_unnamed, current_os_id, drop_current};
 use current::{set_current, try_with_current};
 
 mod spawnhook;
@@ -205,6 +207,7 @@ pub use self::local::{AccessError, LocalKey};
 #[doc(hidden)]
 #[unstable(feature = "thread_local_internals", issue = "none")]
 pub mod local_impl {
+    pub use super::local::thread_local_process_attrs;
     pub use crate::sys::thread_local::*;
 }
 
@@ -550,7 +553,7 @@ impl Builder {
             }
 
             if let Some(name) = their_thread.cname() {
-                imp::Thread::set_name(name);
+                imp::set_name(name);
             }
 
             let f = f.into_inner();
@@ -763,7 +766,7 @@ where
 /// [`Mutex`]: crate::sync::Mutex
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn yield_now() {
-    imp::Thread::yield_now()
+    imp::yield_now()
 }
 
 /// Determines whether the current thread is unwinding because of panic.
@@ -884,7 +887,7 @@ pub fn sleep_ms(ms: u32) {
 /// ```
 #[stable(feature = "thread_sleep", since = "1.4.0")]
 pub fn sleep(dur: Duration) {
-    imp::Thread::sleep(dur)
+    imp::sleep(dur)
 }
 
 /// Puts the current thread to sleep until the specified deadline has passed.
@@ -983,7 +986,7 @@ pub fn sleep(dur: Duration) {
 /// ```
 #[unstable(feature = "thread_sleep_until", issue = "113752")]
 pub fn sleep_until(deadline: Instant) {
-    imp::Thread::sleep_until(deadline)
+    imp::sleep_until(deadline)
 }
 
 /// Used to ensure that `park` and `park_timeout` do not unwind, as that can
@@ -1021,13 +1024,23 @@ impl Drop for PanicGuard {
 ///   specifying a maximum time to block the thread for.
 ///
 /// * The [`unpark`] method on a [`Thread`] atomically makes the token available
-///   if it wasn't already. Because the token is initially absent, [`unpark`]
-///   followed by [`park`] will result in the second call returning immediately.
-///
-/// The API is typically used by acquiring a handle to the current thread,
-/// placing that handle in a shared data structure so that other threads can
-/// find it, and then `park`ing in a loop. When some desired condition is met, another
-/// thread calls [`unpark`] on the handle.
+///   if it wasn't already. Because the token can be held by a thread even if it is currently not
+///   parked, [`unpark`] followed by [`park`] will result in the second call returning immediately.
+///   However, note that to rely on this guarantee, you need to make sure that your `unpark` happens
+///   after all `park` that may be done by other data structures!
+///
+/// The API is typically used by acquiring a handle to the current thread, placing that handle in a
+/// shared data structure so that other threads can find it, and then `park`ing in a loop. When some
+/// desired condition is met, another thread calls [`unpark`] on the handle. The last bullet point
+/// above guarantees that even if the `unpark` occurs before the thread is finished `park`ing, it
+/// will be woken up properly.
+///
+/// Note that the coordination via the shared data structure is crucial: If you `unpark` a thread
+/// without first establishing that it is about to be `park`ing within your code, that `unpark` may
+/// get consumed by a *different* `park` in the same thread, leading to a deadlock. This also means
+/// you must not call unknown code between setting up for parking and calling `park`; for instance,
+/// if you invoke `println!`, that may itself call `park` and thus consume your `unpark` and cause a
+/// deadlock.
 ///
 /// The motivation for this design is twofold:
 ///
@@ -1058,21 +1071,24 @@ impl Drop for PanicGuard {
 ///
 /// ```
 /// use std::thread;
-/// use std::sync::{Arc, atomic::{Ordering, AtomicBool}};
+/// use std::sync::atomic::{Ordering, AtomicBool};
 /// use std::time::Duration;
 ///
-/// let flag = Arc::new(AtomicBool::new(false));
-/// let flag2 = Arc::clone(&flag);
+/// static QUEUED: AtomicBool = AtomicBool::new(false);
+/// static FLAG: AtomicBool = AtomicBool::new(false);
 ///
 /// let parked_thread = thread::spawn(move || {
+///     println!("Thread spawned");
+///     // Signal that we are going to `park`. Between this store and our `park`, there may
+///     // be no other `park`, or else that `park` could consume our `unpark` token!
+///     QUEUED.store(true, Ordering::Release);
 ///     // We want to wait until the flag is set. We *could* just spin, but using
 ///     // park/unpark is more efficient.
-///     while !flag2.load(Ordering::Relaxed) {
-///         println!("Parking thread");
+///     while !FLAG.load(Ordering::Acquire) {
+///         // We can *not* use `println!` here since that could use thread parking internally.
 ///         thread::park();
 ///         // We *could* get here spuriously, i.e., way before the 10ms below are over!
 ///         // But that is no problem, we are in a loop until the flag is set anyway.
-///         println!("Thread unparked");
 ///     }
 ///     println!("Flag received");
 /// });
@@ -1080,11 +1096,22 @@ impl Drop for PanicGuard {
 /// // Let some time pass for the thread to be spawned.
 /// thread::sleep(Duration::from_millis(10));
 ///
+/// // Ensure the thread is about to park.
+/// // This is crucial! It guarantees that the `unpark` below is not consumed
+/// // by some other code in the parked thread (e.g. inside `println!`).
+/// while !QUEUED.load(Ordering::Acquire) {
+///     // Spinning is of course inefficient; in practice, this would more likely be
+///     // a dequeue where we have no work to do if there's nobody queued.
+///     std::hint::spin_loop();
+/// }
+///
 /// // Set the flag, and let the thread wake up.
-/// // There is no race condition here, if `unpark`
+/// // There is no race condition here: if `unpark`
 /// // happens first, `park` will return immediately.
+/// // There is also no other `park` that could consume this token,
+/// // since we waited until the other thread got queued.
 /// // Hence there is no risk of a deadlock.
-/// flag.store(true, Ordering::Relaxed);
+/// FLAG.store(true, Ordering::Release);
 /// println!("Unpark the thread");
 /// parked_thread.thread().unpark();
 ///
@@ -1494,10 +1521,14 @@ impl Thread {
     /// ```
     /// use std::thread;
     /// use std::time::Duration;
+    /// use std::sync::atomic::{AtomicBool, Ordering};
+    ///
+    /// static QUEUED: AtomicBool = AtomicBool::new(false);
     ///
     /// let parked_thread = thread::Builder::new()
     ///     .spawn(|| {
     ///         println!("Parking thread");
+    ///         QUEUED.store(true, Ordering::Release);
     ///         thread::park();
     ///         println!("Thread unparked");
     ///     })
@@ -1506,6 +1537,15 @@ impl Thread {
     /// // Let some time pass for the thread to be spawned.
     /// thread::sleep(Duration::from_millis(10));
     ///
+    /// // Wait until the other thread is queued.
+    /// // This is crucial! It guarantees that the `unpark` below is not consumed
+    /// // by some other code in the parked thread (e.g. inside `println!`).
+    /// while !QUEUED.load(Ordering::Acquire) {
+    ///     // Spinning is of course inefficient; in practice, this would more likely be
+    ///     // a dequeue where we have no work to do if there's nobody queued.
+    ///     std::hint::spin_loop();
+    /// }
+    ///
     /// println!("Unpark the thread");
     /// parked_thread.thread().unpark();
     ///
diff --git a/library/std/src/thread/tests.rs b/library/std/src/thread/tests.rs
index ae889f1e778..2117f5f93ce 100644
--- a/library/std/src/thread/tests.rs
+++ b/library/std/src/thread/tests.rs
@@ -287,6 +287,8 @@ fn test_park_unpark_called_other_thread() {
     for _ in 0..10 {
         let th = thread::current();
 
+        // Here we rely on `thread::spawn` (specifically the part that runs after spawning
+        // the thread) to not consume the parking token.
         let _guard = thread::spawn(move || {
             super::sleep(Duration::from_millis(50));
             th.unpark();
@@ -316,6 +318,8 @@ fn test_park_timeout_unpark_called_other_thread() {
     for _ in 0..10 {
         let th = thread::current();
 
+        // Here we rely on `thread::spawn` (specifically the part that runs after spawning
+        // the thread) to not consume the parking token.
         let _guard = thread::spawn(move || {
             super::sleep(Duration::from_millis(50));
             th.unpark();
diff --git a/library/std/src/time.rs b/library/std/src/time.rs
index 84fbb4c2fe4..31187adb6fe 100644
--- a/library/std/src/time.rs
+++ b/library/std/src/time.rs
@@ -551,13 +551,8 @@ impl SystemTime {
     /// println!("{difference:?}");
     /// ```
     #[stable(feature = "time2", since = "1.8.0")]
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn duration_since(&self, earlier: SystemTime) -> Result<Duration, SystemTimeError> {
-        // FIXME: map_err in const
-        match self.0.sub_time(&earlier.0) {
-            Ok(time) => Ok(time),
-            Err(err) => Err(SystemTimeError(err)),
-        }
+    pub fn duration_since(&self, earlier: SystemTime) -> Result<Duration, SystemTimeError> {
+        self.0.sub_time(&earlier.0).map_err(SystemTimeError)
     }
 
     /// Returns the difference from this system time to the
@@ -594,8 +589,7 @@ impl SystemTime {
     /// `SystemTime` (which means it's inside the bounds of the underlying data structure), `None`
     /// otherwise.
     #[stable(feature = "time_checked_add", since = "1.34.0")]
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_add(&self, duration: Duration) -> Option<SystemTime> {
+    pub fn checked_add(&self, duration: Duration) -> Option<SystemTime> {
         self.0.checked_add_duration(&duration).map(SystemTime)
     }
 
@@ -603,15 +597,13 @@ impl SystemTime {
     /// `SystemTime` (which means it's inside the bounds of the underlying data structure), `None`
     /// otherwise.
     #[stable(feature = "time_checked_add", since = "1.34.0")]
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn checked_sub(&self, duration: Duration) -> Option<SystemTime> {
+    pub fn checked_sub(&self, duration: Duration) -> Option<SystemTime> {
         self.0.checked_sub_duration(&duration).map(SystemTime)
     }
 }
 
 #[stable(feature = "time2", since = "1.8.0")]
-#[rustc_const_unstable(feature = "const_ops", issue = "143802")]
-impl const Add<Duration> for SystemTime {
+impl Add<Duration> for SystemTime {
     type Output = SystemTime;
 
     /// # Panics
@@ -624,16 +616,14 @@ impl const Add<Duration> for SystemTime {
 }
 
 #[stable(feature = "time_augmented_assignment", since = "1.9.0")]
-#[rustc_const_unstable(feature = "const_ops", issue = "143802")]
-impl const AddAssign<Duration> for SystemTime {
+impl AddAssign<Duration> for SystemTime {
     fn add_assign(&mut self, other: Duration) {
         *self = *self + other;
     }
 }
 
 #[stable(feature = "time2", since = "1.8.0")]
-#[rustc_const_unstable(feature = "const_ops", issue = "143802")]
-impl const Sub<Duration> for SystemTime {
+impl Sub<Duration> for SystemTime {
     type Output = SystemTime;
 
     fn sub(self, dur: Duration) -> SystemTime {
@@ -642,8 +632,7 @@ impl const Sub<Duration> for SystemTime {
 }
 
 #[stable(feature = "time_augmented_assignment", since = "1.9.0")]
-#[rustc_const_unstable(feature = "const_ops", issue = "143802")]
-impl const SubAssign<Duration> for SystemTime {
+impl SubAssign<Duration> for SystemTime {
     fn sub_assign(&mut self, other: Duration) {
         *self = *self - other;
     }
@@ -710,8 +699,7 @@ impl SystemTimeError {
     /// ```
     #[must_use]
     #[stable(feature = "time2", since = "1.8.0")]
-    #[rustc_const_unstable(feature = "const_system_time", issue = "144517")]
-    pub const fn duration(&self) -> Duration {
+    pub fn duration(&self) -> Duration {
         self.0
     }
 }