3 files changed, 33 insertions, 3 deletions
diff --git a/src/ci/scripts/install-clang.sh b/src/ci/scripts/install-clang.sh
index a9528e92915..657e1492a6d 100755
--- a/src/ci/scripts/install-clang.sh
+++ b/src/ci/scripts/install-clang.sh
@@ -56,9 +56,19 @@ elif isWindows && ! isKnownToBeMingwBuild; then
 
     mkdir -p citools/clang-rust
     cd citools
-    retry curl -f "${MIRRORS_BASE}/LLVM-${LLVM_VERSION}-win64.exe" \
-        -o "LLVM-${LLVM_VERSION}-win64.exe"
-    7z x -oclang-rust/ "LLVM-${LLVM_VERSION}-win64.exe"
+
+    if [[ "${CI_JOB_NAME}" = *aarch64* ]]; then
+        suffix=woa64
+
+        # On Arm64, the Ring crate requires that Clang be on the PATH.
+        # https://github.com/briansmith/ring/blob/main/BUILDING.md
+        ciCommandAddPath "$(cygpath -m "$(pwd)/clang-rust/bin")"
+    else
+        suffix=win64
+    fi
+    retry curl -f "${MIRRORS_BASE}/LLVM-${LLVM_VERSION}-${suffix}.exe" \
+        -o "LLVM-${LLVM_VERSION}-${suffix}.exe"
+    7z x -oclang-rust/ "LLVM-${LLVM_VERSION}-${suffix}.exe"
     ciCommandSetEnv RUST_CONFIGURE_ARGS \
         "${RUST_CONFIGURE_ARGS} --set llvm.clang-cl=$(pwd)/clang-rust/bin/clang-cl.exe"
 
diff --git a/src/ci/scripts/install-mingw.sh b/src/ci/scripts/install-mingw.sh
index ad852071f29..ed87628659b 100755
--- a/src/ci/scripts/install-mingw.sh
+++ b/src/ci/scripts/install-mingw.sh
@@ -43,4 +43,9 @@ if isWindows && isKnownToBeMingwBuild; then
     curl -o mingw.7z "${MIRRORS_BASE}/${mingw_archive}"
     7z x -y mingw.7z > /dev/null
     ciCommandAddPath "$(cygpath -m "$(pwd)/${mingw_dir}/bin")"
+
+    # Initialize mingw for the user.
+    # This should be done by github but isn't for some reason.
+    # (see https://github.com/actions/runner-images/issues/12600)
+    /c/msys64/usr/bin/bash -lc ' '
 fi
diff --git a/src/ci/scripts/install-rust.sh b/src/ci/scripts/install-rust.sh
new file mode 100755
index 00000000000..e4aee98c9fb
--- /dev/null
+++ b/src/ci/scripts/install-rust.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+
+# The Arm64 Windows Runner does not have Rust already installed
+# https://github.com/actions/partner-runner-images/issues/77
+
+set -euo pipefail
+IFS=$'\n\t'
+
+source "$(cd "$(dirname "$0")" && pwd)/../shared.sh"
+
+if [[ "${CI_JOB_NAME}" = *aarch64* ]] && isWindows; then
+    curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | \
+    sh -s -- -y -q --default-host aarch64-pc-windows-msvc
+    ciCommandAddPath "${USERPROFILE}/.cargo/bin"
+fi