diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -537,7 +537,7 @@
   # in the dylib. C++20 is needed to use char8_t.
   set_target_properties(${target} PROPERTIES
     CXX_STANDARD 20
-    CXX_STANDARD_REQUIRED NO
+	CXX_STANDARD_REQUIRED YES
     CXX_EXTENSIONS NO)
 
   # When building the dylib, don't warn for unavailable aligned allocation
diff --git a/libcxx/benchmarks/CMakeLists.txt b/libcxx/benchmarks/CMakeLists.txt
--- a/libcxx/benchmarks/CMakeLists.txt
+++ b/libcxx/benchmarks/CMakeLists.txt
@@ -145,7 +145,7 @@
           RUNTIME_OUTPUT_DIRECTORY "${BENCHMARK_OUTPUT_DIR}"
           COMPILE_FLAGS "${BENCHMARK_TEST_LIBCXX_COMPILE_FLAGS}"
           LINK_FLAGS "${BENCHMARK_TEST_LIBCXX_LINK_FLAGS}"
-          CXX_STANDARD 17
+          CXX_STANDARD 20
           CXX_STANDARD_REQUIRED YES
           CXX_EXTENSIONS NO)
   cxx_link_system_libraries(${libcxx_target})
@@ -175,7 +175,7 @@
           INCLUDE_DIRECTORIES ""
           COMPILE_FLAGS "${BENCHMARK_TEST_NATIVE_COMPILE_FLAGS}"
           LINK_FLAGS "${BENCHMARK_TEST_NATIVE_LINK_FLAGS}"
-          CXX_STANDARD 17
+          CXX_STANDARD 20
           CXX_STANDARD_REQUIRED YES
           CXX_EXTENSIONS NO)
   endif()