diff --git a/.github/workflows/gh-actions.yml b/.github/workflows/gh-actions.yml
index 55b259da..8b463989 100644
--- a/.github/workflows/gh-actions.yml
+++ b/.github/workflows/gh-actions.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ "master" ]
 
+env:
+  SCCACHE_GHA_ENABLED: "true"
+
 jobs:
   build:
     name: ${{ matrix.config.name }} — ${{ matrix.build_type }}
@@ -28,6 +31,10 @@ jobs:
     - uses: actions/checkout@v4
       with:
         submodules: true
+        fetch-depth: 1
+
+    - name: Setup sccache
+      uses: mozilla-actions/sccache-action@v0.0.9
 
     - name: Setup latest Xcode
       if: matrix.config.name == 'Apple-Clang'
@@ -42,13 +49,25 @@ jobs:
         which git
         git --version
 
-    - name: Install LLVM/Clang 21
+    - name: Cache LLVM 21
+      id: cache-llvm
       if: matrix.config.name == 'Clang'
+      uses: actions/cache@v4
+      with:
+        path: /usr/lib/llvm-21
+        key: llvm-21-${{ runner.os }}-${{ hashFiles('.github/workflows/gh-actions.yml') }}
+
+    - name: Install LLVM/Clang 21
+      if: matrix.config.name == 'Clang' && steps.cache-llvm.outputs.cache-hit != 'true'
       # https://apt.llvm.org
       run: |
         wget https://apt.llvm.org/llvm.sh
         chmod u+x llvm.sh
         sudo ./llvm.sh 21 all
+
+    - name: Set LLVM/Clang 21 env vars
+      if: matrix.config.name == 'Clang'
+      run: |
         echo "PATH=/usr/lib/llvm-21/bin:$PATH" >> $GITHUB_ENV
         echo "LLVM_PATH=/usr/lib/llvm-21" >> $GITHUB_ENV
         echo "LD_LIBRARY_PATH=/usr/lib/llvm-21/lib" >> $GITHUB_ENV
@@ -60,10 +79,7 @@ jobs:
       if: matrix.config.name == 'GCC'
       run: |
         apt-get update
-        apt-get install -y ninja-build
-        cmake_ver=3.31.4
-        wget -qO- "https://github.com/Kitware/CMake/releases/download/v${cmake_ver}/cmake-${cmake_ver}-linux-x86_64.tar.gz" | tar xz --strip-components=1 -C /usr/local
-        cmake --version
+        apt-get install -y ninja-build cmake
 
     - name: Set reusable strings
       id: strings
@@ -79,6 +95,8 @@ jobs:
         -DCMAKE_CXX_COMPILER=${{ matrix.config.cxx }}
         -DCMAKE_C_COMPILER=${{ matrix.config.cc }}
         -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
+        -DCMAKE_C_COMPILER_LAUNCHER=sccache
+        -DCMAKE_CXX_COMPILER_LAUNCHER=sccache
         -DGitHubCIRun=true
         -S ${{ steps.strings.outputs.source-dir }}