Index: libcxx/src/chrono.cpp
===================================================================
--- libcxx/src/chrono.cpp
+++ libcxx/src/chrono.cpp
@@ -28,7 +28,7 @@
 #    include <winapifamily.h>
 #  endif
 #else
-#  if !defined(CLOCK_REALTIME)
+#  if !defined(CLOCK_REALTIME) || !defined(_LIBCPP_USE_CLOCK_GETTIME)
 #    include <sys/time.h>        // for gettimeofday and timeval
 #  endif // !defined(CLOCK_REALTIME)
 #endif // defined(_LIBCPP_WIN32API)
@@ -74,7 +74,7 @@
                        static_cast<__int64>(ft.dwLowDateTime)};
   return time_point(duration_cast<duration>(d - nt_to_unix_epoch));
 #else
-#if defined(CLOCK_REALTIME)
+#if defined(CLOCK_REALTIME) && defined(_LIBCPP_USE_CLOCK_GETTIME)
   struct timespec tp;
   if (0 != clock_gettime(CLOCK_REALTIME, &tp))
     __throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed");