4 files changed, 8 insertions, 2 deletions
diff --git a/library/std/src/io/error/repr_bitpacked.rs b/library/std/src/io/error/repr_bitpacked.rs
index 6f8d5e37775..c9d3934ad70 100644
--- a/library/std/src/io/error/repr_bitpacked.rs
+++ b/library/std/src/io/error/repr_bitpacked.rs
@@ -104,7 +104,6 @@
 
 use super::{Custom, ErrorData, ErrorKind, RawOsError, SimpleMessage};
 use core::marker::PhantomData;
-use core::mem::{align_of, size_of};
 use core::ptr::{self, NonNull};
 
 // The 2 least-significant bits are used as tag.
diff --git a/library/std/src/os/unix/net/ancillary.rs b/library/std/src/os/unix/net/ancillary.rs
index 0597fdcbd72..fe8e2be9372 100644
--- a/library/std/src/os/unix/net/ancillary.rs
+++ b/library/std/src/os/unix/net/ancillary.rs
@@ -3,7 +3,7 @@
 use super::{sockaddr_un, SocketAddr};
 use crate::io::{self, IoSlice, IoSliceMut};
 use crate::marker::PhantomData;
-use crate::mem::{size_of, zeroed};
+use crate::mem::zeroed;
 use crate::os::unix::io::RawFd;
 use crate::path::Path;
 use crate::ptr::{eq, read_unaligned};
diff --git a/library/std/src/prelude/common.rs b/library/std/src/prelude/common.rs
index 01936734d75..ceee3e33c3e 100644
--- a/library/std/src/prelude/common.rs
+++ b/library/std/src/prelude/common.rs
@@ -14,6 +14,9 @@ pub use crate::ops::{Drop, Fn, FnMut, FnOnce};
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)]
 pub use crate::mem::drop;
+#[stable(feature = "size_of_prelude", since = "CURRENT_RUSTC_VERSION")]
+#[doc(no_inline)]
+pub use crate::mem::{align_of, align_of_val, size_of, size_of_val};
 
 // Re-exported types and traits
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/std/src/prelude/mod.rs b/library/std/src/prelude/mod.rs
index 0bdbab716ad..2d4639342bf 100644
--- a/library/std/src/prelude/mod.rs
+++ b/library/std/src/prelude/mod.rs
@@ -36,6 +36,10 @@
 //!   operations for both destructors and overloading `()`.
 //! * <code>[std::mem]::[drop]</code>, a convenience function for explicitly
 //!   dropping a value.
+//! * <code>[std::mem]::{[size_of], [size_of_val]}</code>, to get the size of
+//!   a type or value.
+//! * <code>[std::mem]::{[align_of], [align_of_val]}</code>, to get the
+//!   alignment of a type or value.
 //! * <code>[std::boxed]::[Box]</code>, a way to allocate values on the heap.
 //! * <code>[std::borrow]::[ToOwned]</code>, the conversion trait that defines
 //!   [`to_owned`], the generic method for creating an owned type from a