diff --git a/llvm/lib/Transforms/Makefile b/llvm/lib/Transforms/Makefile
index bf270831083b..5fe1eeb5c752 100644
--- a/llvm/lib/Transforms/Makefile
+++ b/llvm/lib/Transforms/Makefile
@@ -10,10 +10,11 @@
 LEVEL = ../..
 PARALLEL_DIRS = Utils Instrumentation Scalar IPO Hello
 
+include $(LEVEL)/Makefile.config
+
 # No support for plugins on windows targets
 ifeq ($(OS), $(filter $(OS), Cygwin MingW))
-  PARALLEL_DIRS = $(filter-out Hello, $(PARALLEL_DIRS))
+  PARALLEL_DIRS := $(filter-out Hello, $(PARALLEL_DIRS))
 endif
 
 include $(LEVEL)/Makefile.common
-