Index: libcxx/test/support/platform_support.h
===================================================================
--- libcxx/test/support/platform_support.h
+++ libcxx/test/support/platform_support.h
@@ -42,6 +42,10 @@
 #   include <unistd.h> // close
 #endif
 
+#if defined(_CS_GNU_LIBC_VERSION)
+# include <string.h>
+#endif
+
 #if defined(_NEWLIB_VERSION) && defined(__STRICT_ANSI__)
 // Newlib provides this, but in the header it's under __STRICT_ANSI__
 extern "C" {