diff --git a/arch/microblaze/lib/fastcopy.S b/arch/microblaze/lib/fastcopy.S
index fdc48bb065d8..62021d7e249e 100644
--- a/arch/microblaze/lib/fastcopy.S
+++ b/arch/microblaze/lib/fastcopy.S
@@ -29,6 +29,10 @@
  *	between mem locations with size of xfer spec'd in bytes
  */
 
+#ifdef __MICROBLAZEEL__
+#error Microblaze LE not support ASM optimized lib func. Disable OPT_LIB_ASM.
+#endif
+
 #include <linux/linkage.h>
 	.text
 	.globl	memcpy