diff --git a/gcc/config/xm-alloca.h b/gcc/config/xm-alloca.h
new file mode 100644
index 00000000000..3dbdc37a1f0
--- /dev/null
+++ b/gcc/config/xm-alloca.h
@@ -0,0 +1,4 @@
+/* If not compiled with GNU C, use the portable alloca.  */
+#ifndef __GNUC__
+#define USE_C_ALLOCA
+#endif