diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e7453131f69..3890fad861e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-10-08  Jan Hubicka  <hubicka@ucw.cz>
+
+	* i386.c (ix86_expand_set_or_movmem): Disable 512bit loops for targets
+	that preffer 128bit.
+
 2017-10-08  Jan Hubicka  <hubicka@ucw.cz>
 
 	* i386.c (has_dispatch): Disable for Ryzen.
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 8613aa8fa66..1ee8351c21f 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -28947,6 +28947,9 @@ ix86_expand_set_or_movmem (rtx dst, rtx src, rtx count_exp, rtx val_exp,
 	     && optab_handler (mov_optab, wider_mode) != CODE_FOR_nothing)
 	move_mode = wider_mode;
 
+      if (TARGET_AVX128_OPTIMAL && GET_MODE_BITSIZE (move_mode) > 128)
+	move_mode = TImode;
+
       /* Find the corresponding vector mode with the same size as MOVE_MODE.
 	 MOVE_MODE is an integer mode at the moment (SI, DI, TI, etc.).  */
       if (GET_MODE_SIZE (move_mode) > GET_MODE_SIZE (word_mode))