--- a/jdk/make/Tools.gmk	Fri Jun 02 13:38:43 2017 -0700
+++ b/jdk/make/Tools.gmk	Wed Jul 05 23:38:35 2017 +0200
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2011, 2016, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2011, 2017, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # This code is free software; you can redistribute it and/or modify it
@@ -28,6 +28,9 @@
 
 include JavaCompilation.gmk
 
+# Hook to include the corresponding custom file, if present.
+$(eval $(call IncludeCustomExtension, jdk, Tools.gmk))
+
 ################################################################################
 # To avoid reevaluating the compilation setup for the tools each time this file
 # is included, the actual compilation is handled by CompileTools.gmk. The