diff --git a/libcxx/cmake/caches/Generic-cxx23.cmake b/libcxx/cmake/caches/Generic-cxx23-no-modules.cmake
copy from libcxx/cmake/caches/Generic-cxx23.cmake
copy to libcxx/cmake/caches/Generic-cxx23-no-modules.cmake
--- a/libcxx/cmake/caches/Generic-cxx23.cmake
+++ b/libcxx/cmake/caches/Generic-cxx23-no-modules.cmake
@@ -1,2 +1,3 @@
+set(LIBCXX_ENABLE_STD_MODULES OFF CACHE BOOL "")
 set(LIBCXX_TEST_PARAMS "std=c++23" CACHE STRING "")
 set(LIBCXXABI_TEST_PARAMS "${LIBCXX_TEST_PARAMS}" CACHE STRING "")
diff --git a/libcxx/cmake/caches/Generic-cxx23.cmake b/libcxx/cmake/caches/Generic-cxx23.cmake
--- a/libcxx/cmake/caches/Generic-cxx23.cmake
+++ b/libcxx/cmake/caches/Generic-cxx23.cmake
@@ -1,2 +1,3 @@
+set(LIBCXX_ENABLE_STD_MODULES ON CACHE BOOL "") # TODO MODULES Remove when enabled automatically.
 set(LIBCXX_TEST_PARAMS "std=c++23" CACHE STRING "")
 set(LIBCXXABI_TEST_PARAMS "${LIBCXX_TEST_PARAMS}" CACHE STRING "")
diff --git a/libcxx/cmake/caches/Generic-module-std-cxx23.cmake b/libcxx/cmake/caches/Generic-module-std-cxx23.cmake
deleted file mode 100644
--- a/libcxx/cmake/caches/Generic-module-std-cxx23.cmake
+++ /dev/null
@@ -1,4 +0,0 @@
-set(LIBCXX_ENABLE_STD_MODULES ON CACHE BOOL "")
-set(LIBCXX_TEST_PARAMS "std=c++23" CACHE STRING "")
-set(LIBCXXABI_TEST_PARAMS "std=c++23" CACHE STRING "")
-
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
@@ -146,27 +146,6 @@
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "C++23 Module std"
-    command: "libcxx/utils/ci/run-buildbot generic-module-std-cxx23"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    env:
-        # Note modules require and absolute path for clang-scan-deps
-        # https://github.com/llvm/llvm-project/issues/61006
-        CC: "/usr/lib/llvm-${LLVM_HEAD_VERSION}/bin/clang"
-        CXX: "/usr/lib/llvm-${LLVM_HEAD_VERSION}/bin/clang++"
-        CMAKE: "/opt/bin/cmake"
-        ENABLE_CLANG_TIDY: "On"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
   - label: "C++11"
     command: "libcxx/utils/ci/run-buildbot generic-cxx11"
     artifact_paths:
@@ -214,8 +193,11 @@
       - "**/test-results.xml"
       - "**/*.abilist"
     env:
-        CC: "clang-${LLVM_HEAD_VERSION}"
-        CXX: "clang++-${LLVM_HEAD_VERSION}"
+        # Note modules require and absolute path for clang-scan-deps
+        # https://github.com/llvm/llvm-project/issues/61006
+        CC: "/usr/lib/llvm-${LLVM_HEAD_VERSION}/bin/clang"
+        CXX: "/usr/lib/llvm-${LLVM_HEAD_VERSION}/bin/clang++"
+        CMAKE: "/opt/bin/cmake"
         ENABLE_CLANG_TIDY: "On"
     agents:
       queue: "libcxx-builders"
@@ -300,7 +282,7 @@
     timeout_in_minutes: 120
 
   - label: "Clang 15"
-    command: "libcxx/utils/ci/run-buildbot generic-cxx23"
+    command: "libcxx/utils/ci/run-buildbot generic-cxx23-no-modules"
     artifact_paths:
       - "**/test-results.xml"
       - "**/*.abilist"
@@ -318,7 +300,7 @@
     timeout_in_minutes: 120
 
   - label: "Clang 16"
-    command: "libcxx/utils/ci/run-buildbot generic-cxx23"
+    command: "libcxx/utils/ci/run-buildbot generic-cxx23-no-modules"
     artifact_paths:
       - "**/test-results.xml"
       - "**/*.abilist"
@@ -341,8 +323,11 @@
       - "**/test-results.xml"
       - "**/*.abilist"
     env:
-        CC: "clang-17"
-        CXX: "clang++-17"
+        # Note modules require and absolute path for clang-scan-deps
+        # https://github.com/llvm/llvm-project/issues/61006
+        CC: "/usr/lib/llvm-17/bin/clang"
+        CXX: "/usr/lib/llvm-17/bin/clang++"
+        CMAKE: "/opt/bin/cmake"
         ENABLE_CLANG_TIDY: "On"
     agents:
       queue: "libcxx-builders"
@@ -1101,7 +1086,7 @@
   - group: ":freebsd: FreeBSD"
     steps:
     - label: "FreeBSD 13 amd64"
-      command: "libcxx/utils/ci/run-buildbot generic-cxx23"
+      command: "libcxx/utils/ci/run-buildbot generic-cxx23-no-modules"
       artifact_paths:
         - "**/test-results.xml"
         - "**/*.abilist"
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
@@ -414,12 +414,6 @@
     check-runtimes
     check-abi-list
 ;;
-generic-module-std-cxx23)
-    clean
-    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-module-std-cxx23.cmake"
-    check-runtimes
-    check-abi-list
-;;
 #
 # Parts removed
 #
@@ -465,6 +459,15 @@
     check-runtimes
     check-abi-list
 ;;
+# Using C++20 modules requires Clang 17 or newer.
+# This is a transition build for older Clang versions.
+# TODO(LLVM 20) Remove this build and cache file.
+generic-cxx23-no-modules)
+    clean
+    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-cxx23-no-modules.cmake"
+    check-runtimes
+    check-abi-list
+;;
 #
 # Other miscellaneous jobs
 #