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
@@ -83,6 +83,7 @@
           -GNinja -DCMAKE_MAKE_PROGRAM="${NINJA}" \
           -DCMAKE_BUILD_TYPE=RelWithDebInfo \
           -DCMAKE_INSTALL_PREFIX="${INSTALL_DIR}" \
+          -DLIBCXX_ENABLE_WERROR=YES \
           -DLLVM_LIT_ARGS="-sv --show-unsupported --xunit-xml-output test-results.xml" \
           "${@}"
 }
@@ -294,7 +295,8 @@
     export CXX=g++-11
     clean
     generate-cmake -DLIBCXX_TEST_CONFIG="llvm-libc++-shared-gcc.cfg.in" \
-                   -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
+                   -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in" \
+                   -DLIBCXX_ENABLE_WERROR=NO
     check-runtimes
 ;;
 generic-gcc-cxx11)
@@ -303,7 +305,8 @@
     clean
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-cxx11.cmake" \
                    -DLIBCXX_TEST_CONFIG="llvm-libc++-shared-gcc.cfg.in" \
-                   -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in"
+                   -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in" \
+                   -DLIBCXX_ENABLE_WERROR=NO
     check-runtimes
 ;;
 generic-asan)