diff --git a/include/llvm/Config/config.h.in b/include/llvm/Config/config.h.in
index bcb1993..dd4f458 100644
--- a/include/llvm/Config/config.h.in
+++ b/include/llvm/Config/config.h.in
@@ -279,6 +279,9 @@
 /* Define to 1 if you have the `strtoq' function. */
 #undef HAVE_STRTOQ
 
+/* Define to 1 if you have the `sysconf' function. */
+#undef HAVE_SYSCONF
+
 /* Define to 1 if you have the <sys/dir.h> header file, and it defines `DIR'.
    */
 #undef HAVE_SYS_DIR_H