diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 1809b26a0109..3de8861f792d 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2014-12-12  Kai Tietz  <ktietz@redhat.com>
+
+	PR c++/63996
+	* constexpr.c (cxx_eval_loop_expr): Don't loop
+	endless on none-constant expression.
+
 2014-12-12  Jason Merrill  <jason@redhat.com>
 
 	PR c++/61402
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 9426d8558e23..732a79cdf182 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -2841,7 +2841,7 @@ cxx_eval_loop_expr (const constexpr_ctx *ctx, tree t,
     {
       cxx_eval_statement_list (ctx, body,
 			       non_constant_p, overflow_p, jump_target);
-      if (returns (jump_target) || breaks (jump_target))
+      if (returns (jump_target) || breaks (jump_target) || *non_constant_p)
 	break;
     }
   if (breaks (jump_target))