diff --git a/include/llvm/Config/config.h.in b/include/llvm/Config/config.h.in
index 8ab67a4f63a..eee2f946148 100644
--- a/include/llvm/Config/config.h.in
+++ b/include/llvm/Config/config.h.in
@@ -470,6 +470,9 @@
 /* Installation directory for man pages */
 #undef LLVM_MANDIR
 
+/* Build multithreading support into LLVM */
+#undef LLVM_MULTITHREADED
+
 /* Define if this is Unixish platform */
 #undef LLVM_ON_UNIX