diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 3900bba6250..7109684c21b 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,8 @@
 2016-09-23  Jakub Jelinek  <jakub@redhat.com>
 
+	* Make-lang.in (check-c++1z): Pass RUNTESTFLAGS down to
+	make check-g++.
+
 	* constexpr.c (call_stack): Remove unnecessary
 	= vNULL initialization of file scope vec.
 
diff --git a/gcc/cp/Make-lang.in b/gcc/cp/Make-lang.in
index cc3337d7eff..84c9ba428f0 100644
--- a/gcc/cp/Make-lang.in
+++ b/gcc/cp/Make-lang.in
@@ -164,7 +164,7 @@ check-c++ : check-g++
 
 # Run the testsuite in C++1z mode.
 check-c++1z:
-	$(MAKE) GXX_TESTSUITE_STDS=1z check-g++
+	$(MAKE) RUNTESTFLAGS="$(RUNTESTFLAGS)" GXX_TESTSUITE_STDS=1z check-g++
 
 # Run the testsuite in all standard conformance levels.
 check-c++-all: