Index: libcxx/CMakeLists.txt
===================================================================
--- libcxx/CMakeLists.txt
+++ libcxx/CMakeLists.txt
@@ -327,13 +327,8 @@
   message(FATAL_ERROR "LIBCXX_BUILD_32_BITS=ON is not supported on this platform.")
 endif()
 
-# Check that this option is not enabled on Apple and emit a usage warning.
 if (LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
-  if (APPLE)
-    message(FATAL_ERROR "LIBCXX_ENABLE_STATIC_ABI_LIBRARY is not supported on OS X")
-  else()
-    message(WARNING "LIBCXX_ENABLE_STATIC_ABI_LIBRARY is an experimental option")
-  endif()
+  message(WARNING "LIBCXX_ENABLE_STATIC_ABI_LIBRARY is an experimental option")
   if (LIBCXX_ENABLE_STATIC AND NOT PYTHONINTERP_FOUND)
     message(FATAL_ERROR "LIBCXX_ENABLE_STATIC_ABI_LIBRARY requires python but it was not found.")
   endif()