+# Don't build compiler-rt, it isn't designed to be built directly.
+DIRS := $(filter-out compiler-rt,$(DIRS))
+
+# Don't build libcxx, it isn't designed to be built directly.
+DIRS := $(filter-out libcxx,$(DIRS))
+
+# DragonEgg may be checked out here but doesn't (yet) build directly.
+DIRS := $(filter-out dragonegg,$(DIRS))
+
+include $(PROJ_SRC_ROOT)/Makefile.rules