diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 08c2c8c3720..609a6a3eab8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-01-09  John David Anglin  <danglin@gcc.gnu.org>
+
+	PR middle-end/68743
+	* match.pd: Require target has function_c99_misc before doing
+	truncl(extend(x)) and trunc(extend(x)) -> extend(truncf(x)), etc.
+	
 2016-01-09  Gerald Pfeifer  <gerald@pfeifer.com>
 
 	* configure.ac (isl_options_set_schedule_serialize_sccs): Also 
diff --git a/gcc/match.pd b/gcc/match.pd
index 64e718cc5c9..069d2718399 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -2784,7 +2784,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 	  BUILT_IN_RINTF BUILT_IN_RINTF)
  /* truncl(extend(x)) and trunc(extend(x)) -> extend(truncf(x)), etc.,
     if x is a float.  */
- (if (optimize && canonicalize_math_p ())
+ (if (optimize && canonicalize_math_p ()
+      && targetm.libc_has_function (function_c99_misc))
   (simplify
    (froms (convert float_value_p@0))
    (convert (tos @0)))))