diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 57a1578caa31..3622483545c5 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2016-12-19  Dominik Vogt  <vogt@linux.vnet.ibm.com>
+
+	* combine.c (change_zero_ext): Skip generation of redundant AND.
+
 2016-12-19  Krister Walfridsson  <krister.walfridsson@gmail.com>
 
 	* config/netbsd.h (LINK_EH_SPEC): Define.
diff --git a/gcc/combine.c b/gcc/combine.c
index 473ffc4a1321..e74ff4c20a1f 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -11289,8 +11289,13 @@ change_zero_ext (rtx pat)
       else
 	continue;
 
-      wide_int mask = wi::mask (size, false, GET_MODE_PRECISION (mode));
-      x = gen_rtx_AND (mode, x, immed_wide_int_const (mask, mode));
+      if (!(GET_CODE (x) == LSHIFTRT
+	    && CONST_INT_P (XEXP (x, 1))
+	    && size + INTVAL (XEXP (x, 1)) == GET_MODE_PRECISION (mode)))
+	{
+	  wide_int mask = wi::mask (size, false, GET_MODE_PRECISION (mode));
+	  x = gen_rtx_AND (mode, x, immed_wide_int_const (mask, mode));
+	}
 
       SUBST (**iter, x);
       changed = true;