diff --git a/tools/diagtool/Makefile b/tools/diagtool/Makefile
index 2f9706ef25..1004dd44c4 100644
--- a/tools/diagtool/Makefile
+++ b/tools/diagtool/Makefile
@@ -1,4 +1,4 @@
-##===- tools/driver/Makefile -------------------------------*- Makefile -*-===##
+##===- tools/diagtool/Makefile -----------------------------*- Makefile -*-===##
 #
 #                     The LLVM Compiler Infrastructure
 #
@@ -16,9 +16,16 @@ TOOL_NO_EXPORTS := 1
 # Don't install this.
 NO_INSTALL = 1
 
+# Include this here so we can get the configuration of the targets that have
+# been configured for construction. We have to do this early so we can set up
+# LINK_COMPONENTS before including Makefile.rules
+include $(CLANG_LEVEL)/../../Makefile.config
+
 LINK_COMPONENTS := support $(TARGETS_TO_BUILD)
 
-USEDLIBS = clangBasic.a clangFrontend.a
+# FIXME: diagtool should be much lighter than this.
+USEDLIBS = clangAST.a clangBasic.a clangDriver.a clangEdit.a clangFrontend.a \
+           clangLex.a clangParse.a clangSema.a clangSerialization.a
 
 include $(CLANG_LEVEL)/Makefile