diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 0000000..8e7dd6c
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,28 @@
+name: build
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: build
+    runs-on: ubuntu-latest
+    steps:
+
+      - name: checkout
+        uses: actions/checkout@v4
+
+      - name: setup-apt-llvm
+        uses: ./
+
+      - name: test-apt-llvm
+        run: |
+          sudo apt install -y \
+            clang-19 \
+            clang-18 \
+            clang-17 \
+            clang-16
diff --git a/action.yml b/action.yml
new file mode 100644
index 0000000..5f4a910
--- /dev/null
+++ b/action.yml
@@ -0,0 +1,8 @@
+name: setup-apt-llvm
+description: Setup apt.llvm.org repositories
+runs:
+  using: composite
+  steps:
+    - if: ${{ runner.os == 'Linux' }}
+      run: ${{ github.action_path }}/setup.sh
+      shell: bash
diff --git a/setup.sh b/setup.sh
new file mode 100755
index 0000000..ac6bc09
--- /dev/null
+++ b/setup.sh
@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+LSB_CODENAME=$(lsb_release -cs)
+
+curl -f -L --retry 5 https://apt.llvm.org/llvm-snapshot.gpg.key | sudo gpg --dearmor -o /usr/share/keyrings/llvm-snapshot.gpg
+
+{
+  echo "deb [signed-by=/usr/share/keyrings/llvm-snapshot.gpg] https://apt.llvm.org/$LSB_CODENAME llvm-toolchain-$LSB_CODENAME main"
+  echo "deb [signed-by=/usr/share/keyrings/llvm-snapshot.gpg] https://apt.llvm.org/$LSB_CODENAME llvm-toolchain-$LSB_CODENAME-18 main"
+  echo "deb [signed-by=/usr/share/keyrings/llvm-snapshot.gpg] https://apt.llvm.org/$LSB_CODENAME llvm-toolchain-$LSB_CODENAME-17 main"
+  echo "deb [signed-by=/usr/share/keyrings/llvm-snapshot.gpg] https://apt.llvm.org/$LSB_CODENAME llvm-toolchain-$LSB_CODENAME-16 main"
+} | sudo tee /etc/apt/sources.list.d/llvm-toolchain.list
+
+sudo apt update