diff --git a/libcxx/include/__config b/libcxx/include/__config
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -273,6 +273,14 @@
 #    define _LIBCPP_HAS_NO_INCOMPLETE_FORMAT
 #  endif
 
+// Make sure the library can be build without transitive includes. This makes
+// it easier to upgrade the library to a newer language standard without build
+// errors. Since users are allowed to define _LIBCPP_REMOVE_TRANSITIVE_INCLUDES
+// it can't be set as a compiler flag in CMake.
+#  if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && defined(_LIBCPP_BUILDING_LIBRARY)
+#    define _LIBCPP_REMOVE_TRANSITIVE_INCLUDES
+#  endif
+
 // Need to detect which libc we're using if we're on Linux.
 #  if defined(__linux__)
 #    include <features.h>