diff --git a/lib/clang/clang.build.mk b/lib/clang/clang.build.mk
index 2cf1e5b8b864..9bcf5064681b 100644
--- a/lib/clang/clang.build.mk
+++ b/lib/clang/clang.build.mk
@@ -196,3 +196,7 @@ Checkers.inc.h: ${CLANG_SRCS}/lib/StaticAnalyzer/Checkers/Checkers.td \
 SRCS+=		${TGHDRS:C/$/.inc.h/}
 DPADD+=		${TGHDRS:C/$/.inc.h/}
 CLEANFILES+=	${TGHDRS:C/$/.inc.h/}
+
+# if we are not doing explicit 'make depend', there is 
+# nothing to cause these to be generated.
+beforebuild: ${SRCS:M*.inc.h}