I really meant to use that AUTOHEADER variable I put in there.

llvm-svn: 8972
diff --git a/llvm/Makefile b/llvm/Makefile
index f3a4ffc..71534d1 100644
--- a/llvm/Makefile
+++ b/llvm/Makefile
@@ -21,5 +21,5 @@
 	cd autoconf && $(AUTOCONF) -o ../configure configure.ac
 
 include/Config/config.h.in: autoconf/configure.ac autoconf/aclocal.m4
-	autoheader -I autoconf autoconf/configure.ac
+	$(AUTOHEADER) -I autoconf autoconf/configure.ac