3 files changed, 6 insertions, 3 deletions
diff --git a/compiler/rustc_codegen_llvm/src/back/archive.rs b/compiler/rustc_codegen_llvm/src/back/archive.rs
index 0619000364b..d4a3e39cef7 100644
--- a/compiler/rustc_codegen_llvm/src/back/archive.rs
+++ b/compiler/rustc_codegen_llvm/src/back/archive.rs
@@ -415,6 +415,7 @@ impl<'a> LlvmArchiveBuilder<'a> {
                 members.as_ptr() as *const &_,
                 true,
                 kind,
+                self.sess.target.arch == "arm64ec",
             );
             let ret = if r.into_result().is_err() {
                 let err = llvm::LLVMRustGetLastError();
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 5509baaa3e9..83158f6f1d5 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -2303,6 +2303,7 @@ extern "C" {
         Members: *const &RustArchiveMember<'_>,
         WriteSymbtab: bool,
         Kind: ArchiveKind,
+        isEC: bool,
     ) -> LLVMRustResult;
     pub fn LLVMRustArchiveMemberNew<'a>(
         Filename: *const c_char,
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index c9e62e504ae..5552b381025 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -270,9 +270,10 @@ pub fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> LLVMFeature<'a> {
             "sve2-bitperm",
             TargetFeatureFoldStrength::EnableOnly("neon"),
         ),
-        // The unaligned-scalar-mem feature was renamed to fast-unaligned-access.
-        ("riscv32" | "riscv64", "fast-unaligned-access") if get_version().0 <= 17 => {
-            LLVMFeature::new("unaligned-scalar-mem")
+        // In LLVM 18, `unaligned-scalar-mem` was merged with `unaligned-vector-mem` into a single feature called
+        // `fast-unaligned-access`. In LLVM 19, it was split back out.
+        ("riscv32" | "riscv64", "unaligned-scalar-mem") if get_version().0 == 18 => {
+            LLVMFeature::new("fast-unaligned-access")
         }
         // For LLVM 18, enable the evex512 target feature if a avx512 target feature is enabled.
         ("x86", s) if get_version().0 >= 18 && s.starts_with("avx512") => {