diff --git a/.gitmodules b/.gitmodules
index 439fde6d76601..a6b053e88ee99 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -24,8 +24,8 @@
 	shallow = true
 [submodule "src/llvm-project"]
 	path = src/llvm-project
-	url = https://github.com/rust-lang/llvm-project.git
-	branch = rustc/20.1-2025-07-13
+	url = https://github.com/nikic/llvm-project.git
+	branch = rust-llvm-21
 	shallow = true
 [submodule "src/doc/embedded-book"]
 	path = src/doc/embedded-book
diff --git a/src/ci/docker/scripts/build-clang.sh b/src/ci/docker/scripts/build-clang.sh
index 536991cc06b7d..ee1a48a5b2f1f 100755
--- a/src/ci/docker/scripts/build-clang.sh
+++ b/src/ci/docker/scripts/build-clang.sh
@@ -5,7 +5,7 @@ set -ex
 source shared.sh
 
 # Try to keep the LLVM version here in sync with src/ci/scripts/install-clang.sh
-LLVM=llvmorg-20.1.0-rc2
+LLVM=llvmorg-21.1.0-rc1
 
 mkdir llvm-project
 cd llvm-project
diff --git a/src/llvm-project b/src/llvm-project
index e8a2ffcf322f4..e4c2cd8f4691d 160000
--- a/src/llvm-project
+++ b/src/llvm-project
@@ -1 +1 @@
-Subproject commit e8a2ffcf322f45b8dce82c65ab27a3e2430a6b51
+Subproject commit e4c2cd8f4691dc7a98af55b34a36d46ceb96e4d7
diff --git a/tests/assembly/nvptx-safe-naming.rs b/tests/assembly/nvptx-safe-naming.rs
index d7b46aadd9cc1..6a6659a4e3047 100644
--- a/tests/assembly/nvptx-safe-naming.rs
+++ b/tests/assembly/nvptx-safe-naming.rs
@@ -1,6 +1,9 @@
 //@ assembly-output: ptx-linker
 //@ compile-flags: --crate-type cdylib -Z unstable-options -Clinker-flavor=llbc
 //@ only-nvptx64
+//@ revisions: LLVM20 LLVM21
+//@ [LLVM21] min-llvm-version: 21
+//@ [LLVM20] max-llvm-major-version: 20
 
 #![feature(abi_ptx)]
 #![no_std]
@@ -15,7 +18,8 @@ extern crate breakpoint_panic_handler;
 #[no_mangle]
 pub unsafe extern "ptx-kernel" fn top_kernel(a: *const u32, b: *mut u32) {
     // CHECK:      call.uni (retval0),
-    // CHECK-NEXT: [[IMPL_FN]]
+    // LLVM20-NEXT: [[IMPL_FN]]
+    // LLVM21-SAME: [[IMPL_FN]]
     *b = deep::private::MyStruct::new(*a).square();
 }