diff --git a/libcxx/utils/ci/buildkite-pipeline.yml b/libcxx/utils/ci/buildkite-pipeline.yml
--- a/libcxx/utils/ci/buildkite-pipeline.yml
+++ b/libcxx/utils/ci/buildkite-pipeline.yml
@@ -255,6 +255,17 @@
         - exit_status: -1  # Agent was lost
           limit: 2
 
+  - label: "Runtimes build"
+    command: "libcxx/utils/ci/run-buildbot runtimes-build"
+    artifact_paths:
+      - "**/test-results.xml"
+    agents:
+      queue: "libcxx-builders"
+    retry:
+      automatic:
+        - exit_status: -1  # Agent was lost
+          limit: 2
+
   - label: "Legacy standalone build"
     command: "libcxx/utils/ci/run-buildbot legacy-standalone"
     artifact_paths:
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -345,6 +345,24 @@
 
     check-cxx-cxxabi
 ;;
+runtimes-build)
+    export CC=clang
+    export CXX=clang++
+
+    clean
+
+    echo "--- Generating CMake"
+    cmake -S "${MONOREPO_ROOT}/llvm" \
+          -B "${BUILD_DIR}" \
+          -GNinja \
+          -DCMAKE_BUILD_TYPE=RelWithDebInfo \
+          -DCMAKE_INSTALL_PREFIX="${INSTALL_DIR}" \
+          -DLLVM_ENABLE_PROJECTS="clang" \
+          -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi" \
+          -DLLVM_RUNTIME_TARGETS="x86_64-unknown-linux"
+
+    check-cxx-cxxabi
+;;
 legacy-standalone)
     export CC=clang
     export CXX=clang++