diff --git a/test/Makefile b/test/Makefile
index a67fcbd..b7cb38a 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -22,16 +22,17 @@
 endif
 endif
 
+# Make sure any extra test suites can find the main site config.
+LIT_ARGS := --param clang_site_config=$(PROJ_OBJ_DIR)/lit.site.cfg
+
 ifdef VG
-  VGARG="--vg"
-else
-  VGARG=
+  LIT_ARGS += "--vg"
 endif
 
 all:: lit.site.cfg
 	@ echo '--- Running clang tests for $(TARGET_TRIPLE) ---'
 	@ $(PYTHON) $(LLVM_SRC_ROOT)/utils/lit/lit.py \
-	  $(TESTARGS) $(TESTDIRS) $(VGARG)
+	  $(LIT_ARGS) $(TESTARGS) $(TESTDIRS)
 
 FORCE: