diff --git a/.cirrus.yml b/.cirrus.yml
deleted file mode 100644
index 00237d1b00e4b1e..000000000000000
--- a/.cirrus.yml
+++ /dev/null
@@ -1,107 +0,0 @@
-environment:
-  CIRRUS_CLONE_DEPTH: 50
-  CLANG_VERSION: '15.0.3' # 15.0.6 requires a more recent libstdc++.so.6 than shipped with Ubuntu 20
-  LLVM_PROJECTS_TO_ENABLE: compiler-rt;lld;bolt
-  # keep these in sync with .github/workflows/ldc-release.yml for Linux x64:
-  LLVM_TARGETS_TO_BUILD: all
-  LLVM_EXPERIMENTAL_TARGETS_TO_BUILD: SPIRV;Xtensa
-  BASE_CMAKE_FLAGS: -DLLVM_ENABLE_TERMINFO=OFF -DLLVM_ENABLE_LIBEDIT=OFF -DLLVM_USE_STATIC_ZSTD=TRUE -DCOMPILER_RT_INCLUDE_TESTS=OFF -DLLVM_INCLUDE_TESTS=OFF -DCOMPILER_RT_USE_LIBCXX=OFF
-  EXTRA_CMAKE_FLAGS: -DLLVM_BINUTILS_INCDIR=/usr/include -DLLVM_STATIC_LINK_CXX_STDLIB=ON
-
-task:
-  name: Ubuntu 20.04 $TASK_NAME_SUFFIX
-  compute_engine_instance:
-    image_project: ubuntu-os-cloud
-    image: family/ubuntu-2004-lts-arm64
-    platform: linux
-    architecture: arm64
-    cpu: 4
-    memory: 8G
-    disk: 20
-  timeout_in: 120m
-  environment:
-    PARALLELISM: 4
-    GITHUB_TOKEN: ENCRYPTED[79b00f4f535df0fdfe3ceea87f9d4ec2ba7628e0c60730b99bcd91c7888af275409f02b2f1bc90015c2cb9cc4fb2dd12]
-    matrix:
-      - TASK_NAME_SUFFIX: aarch64
-        LLVM_ENABLE_ASSERTIONS: 'OFF'
-      - TASK_NAME_SUFFIX: aarch64 withAsserts
-        LLVM_ENABLE_ASSERTIONS: 'ON'
-  install_prerequisites_script: |
-    export DEBIAN_FRONTEND=noninteractive
-    apt-get -q update
-    apt-get -yq install git-core curl xz-utils ninja-build g++ python3 pkg-config binutils-dev libxml2-dev libzstd-dev zlib1g-dev p7zip-full
-    # install a more recent version of CMake
-    curl -fL --retry 3 --max-time 300 -o cmake.tar.gz https://github.com/Kitware/CMake/releases/download/v3.28.4/cmake-3.28.4-linux-aarch64.tar.gz
-    mkdir cmake_bin
-    tar -xf cmake.tar.gz --strip 1 -C cmake_bin
-    rm cmake.tar.gz
-    # download & extract clang
-    curl -fL --retry 3 --max-time 300 -o clang.tar.xz https://github.com/llvm/llvm-project/releases/download/llvmorg-$CLANG_VERSION/clang+llvm-$CLANG_VERSION-aarch64-linux-gnu.tar.xz
-    mkdir clang_bin
-    tar -xf clang.tar.xz --strip 1 -C clang_bin
-    rm clang.tar.xz
-    # make lld the default linker
-    ln -sf "$PWD/clang_bin/bin/ld.lld" /usr/bin/ld
-    ld --version
-  clone_submodules_script: |
-    git submodule update --init --depth $CIRRUS_CLONE_DEPTH
-  build_script: |
-    export PATH="$PWD/cmake_bin/bin:$PATH"
-    export CC="$PWD/clang_bin/bin/clang"
-    export CXX="$PWD/clang_bin/bin/clang++"
-    nproc
-    free
-    cmake --version
-    ninja --version
-    mkdir build
-    cd build
-    cmake -G Ninja ../llvm \
-      -DCMAKE_BUILD_TYPE=Release \
-      -DCMAKE_INSTALL_PREFIX=$PWD/../install \
-      -DLLVM_ENABLE_PROJECTS="$LLVM_PROJECTS_TO_ENABLE" \
-      -DLLVM_TARGETS_TO_BUILD="$LLVM_TARGETS_TO_BUILD" \
-      -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD="$LLVM_EXPERIMENTAL_TARGETS_TO_BUILD" \
-      -DLLVM_ENABLE_ASSERTIONS=$LLVM_ENABLE_ASSERTIONS \
-      $BASE_CMAKE_FLAGS $EXTRA_CMAKE_FLAGS
-    ninja -j$PARALLELISM install
-    cd ..
-  pack_artifact_script: |
-    if [[ "${CIRRUS_TAG:-}" == ldc-v* ]]; then
-      artifactID=${CIRRUS_TAG:5}
-    else
-      artifactID=${CIRRUS_CHANGE_IN_REPO:0:8}
-    fi
-    assertsSuffix=""
-    if [[ "$LLVM_ENABLE_ASSERTIONS" == "ON" ]]; then
-      assertsSuffix="-withAsserts"
-    fi
-    artifactName=llvm-$artifactID-linux-aarch64$assertsSuffix
-    mv install $artifactName
-    chmod -R go=rX $artifactName
-    artifact=$artifactName.tar.xz
-    tar -cf - --owner=0 --group=0 $artifactName | 7za a $artifact -si -txz -mx9 -mmt$PARALLELISM
-    ls -lh $artifact
-  # Upload to GitHub release (only for branches and tags, no PRs)
-  upload_to_github_script: |
-    if [[ "${CIRRUS_TAG:-}" == ldc-v* ]]; then
-      releaseTag=$CIRRUS_TAG
-    elif [[ "${CIRRUS_TAG:-}" == "" && "${CIRRUS_PR:-}" == "" ]]; then
-      releaseTag=CI
-    else
-      echo 'Skipping upload'
-      exit 0
-    fi
-    releaseID="$(set -eo pipefail; curl -fsS https://api.github.com/repos/ldc-developers/llvm-project/releases/tags/"$releaseTag" | grep '^  "id":' | head -n1 || echo "<error>")"
-    if [[ "$releaseID" == "<error>" ]]; then
-      echo "Error: no GitHub release found for tag '$releaseTag'" >&2
-      exit 1
-    fi
-    releaseID=${releaseID:8:-1}
-    artifact=$(ls llvm-*.tar.xz)
-    echo "Uploading $artifact to GitHub release $releaseTag ($releaseID)..."
-    curl -fsS \
-      -H "Authorization: token $GITHUB_TOKEN" \
-      -H "Content-Type: application/octet-stream" \
-      --data-binary @$artifact \
-      https://uploads.github.com/repos/ldc-developers/llvm-project/releases/$releaseID/assets?name=$artifact
diff --git a/.github/actions/1-setup/action.yml b/.github/actions/1-setup/action.yml
index fa87ad182ad511f..e3bb794e9776e14 100644
--- a/.github/actions/1-setup/action.yml
+++ b/.github/actions/1-setup/action.yml
@@ -15,9 +15,8 @@ runs:
         set -eux
         export DEBIAN_FRONTEND=noninteractive
         sudo apt-get -q update
-        sudo apt-get -yq install \
-          git-core cmake g++ binutils-dev libzstd-dev python p7zip-full unzip
-
+        sudo -E apt-get -yq install \
+          git-core curl xz-utils cmake ninja-build g++ python3 pkg-config binutils-dev libxml2-dev libzstd-dev zlib1g-dev p7zip-full unzip
     - name: 'Linux: Download & extract clang' # into ../clang
       if: runner.os == 'Linux'
       shell: bash
@@ -25,8 +24,13 @@ runs:
         set -eux
         cd ..
         version='${{ inputs.clang_version }}'
+        arch='${{ inputs.arch }}'
+        extraSuffix=''
+        if [[ $arch == x86_64 ]]; then
+          extraSuffix='-ubuntu-18.04'
+        fi
         curl -fL --retry 3 --max-time 300 -o clang.tar.xz \
-          https://github.com/llvm/llvm-project/releases/download/llvmorg-$version/clang+llvm-$version-x86_64-linux-gnu-ubuntu-18.04.tar.xz
+          https://github.com/llvm/llvm-project/releases/download/llvmorg-$version/clang+llvm-$version-$arch-linux-gnu$extraSuffix.tar.xz
         mkdir clang
         tar -xf clang.tar.xz --strip 1 -C clang
         rm clang.tar.xz
@@ -64,7 +68,8 @@ runs:
           echo "ASMFLAGS=-m32" >> $GITHUB_ENV
         fi
 
-    - name: Install ninja
+    - name: 'Non-Linux: Install ninja'
+      if: runner.os != 'Linux'
       uses: seanmiddleditch/gha-setup-ninja@v4
 
     - name: 'Windows: Set LDC_VSDIR env variable'
diff --git a/.github/actions/3-package/action.yml b/.github/actions/3-package/action.yml
index c0b165ce23b990e..67ce97e0b97fbcd 100644
--- a/.github/actions/3-package/action.yml
+++ b/.github/actions/3-package/action.yml
@@ -68,8 +68,8 @@ runs:
         echo "ARTIFACT_ID=$artifactID" >> $GITHUB_ENV
         echo "ARTIFACT_NAME=$os-${{ inputs.arch }}$assertsSuffix" >> $GITHUB_ENV
 
-    - name: 'Linux: Pack source dir'
-      if: runner.os == 'Linux' && inputs.os == '' && inputs.with_asserts == 'false'
+    - name: 'Linux x86_64: Pack source dir'
+      if: runner.os == 'Linux' && inputs.os == '' && inputs.arch == 'x86_64' && inputs.with_asserts == 'false'
       shell: bash
       run: |
         set -euxo pipefail
diff --git a/.github/workflows/ldc-release.yml b/.github/workflows/ldc-release.yml
index 93c0bc3689ddff4..e2411321f91271e 100644
--- a/.github/workflows/ldc-release.yml
+++ b/.github/workflows/ldc-release.yml
@@ -33,18 +33,22 @@ jobs:
             os: windows-2022
             arch: x64
             with_asserts: false
+            clang_version: 19.1.3 # the MSVC headers require clang 16+
           - job_name: Windows x64 withAsserts
             os: windows-2022
             arch: x64
             with_asserts: true
+            clang_version: 19.1.3 # the MSVC headers require clang 16+
           - job_name: Windows x86
             os: windows-2022
             arch: x86
             with_asserts: false
+            clang_version: 19.1.3 # the MSVC headers require clang 16+
           - job_name: Windows x86 withAsserts
             os: windows-2022
             arch: x86
             with_asserts: true
+            clang_version: 19.1.3 # the MSVC headers require clang 16+
           - job_name: Linux x86_64
             os: ubuntu-20.04
             arch: x86_64
@@ -53,6 +57,18 @@ jobs:
             os: ubuntu-20.04
             arch: x86_64
             with_asserts: true
+          - job_name: Linux aarch64
+            os: ubuntu-22.04-arm # Ubuntu 20 not natively supported
+            container_image: ubuntu:20.04
+            arch: aarch64
+            with_asserts: false
+            clang_version: 15.0.3 # 15.0.6 requires a more recent libstdc++.so.6 than shipped with Ubuntu 20
+          - job_name: Linux aarch64 withAsserts
+            os: ubuntu-22.04-arm # Ubuntu 20 not natively supported
+            container_image: ubuntu:20.04
+            arch: aarch64
+            with_asserts: true
+            clang_version: 15.0.3 # 15.0.6 requires a more recent libstdc++.so.6 than shipped with Ubuntu 20
           - job_name: macOS arm64
             os: macos-15
             arch: arm64
@@ -71,16 +87,23 @@ jobs:
             with_asserts: true
     name: ${{ matrix.job_name }}
     runs-on: ${{ matrix.os }}
+    container: ${{ matrix.container_image }}
     timeout-minutes: 240
     env:
       MACOSX_DEPLOYMENT_TARGET: ${{ matrix.arch == 'arm64' && '11.0' || '10.12' }}
     steps:
+      - name: 'Container: Install git and sudo'
+        if: matrix.container_image
+        shell: bash
+        run: |
+          set -eux
+          apt-get -q update
+          DEBIAN_FRONTEND=noninteractive apt-get -yq install git-core sudo
       - uses: actions/checkout@v4
       - name: Install prerequisites
         uses: ./.github/actions/1-setup
         with:
-          # on Windows, the MSVC headers require clang 16+
-          clang_version: ${{ runner.os == 'Windows' && '19.1.3' || env.CLANG_VERSION }}
+          clang_version: ${{ matrix.clang_version || env.CLANG_VERSION }}
           arch: ${{ matrix.arch }}
       # BOLT supports ELF binaries only, so include it for Linux packages only
       - name: Build & install LLVM incl. LLD, compiler-rt${{ runner.os == 'Linux' && ', BOLT' || '' }}