diff --git a/llvm/autoconf/configure.ac b/llvm/autoconf/configure.ac
index 7cf02a197ea2..6d968e72dd42 100644
--- a/llvm/autoconf/configure.ac
+++ b/llvm/autoconf/configure.ac
@@ -315,8 +315,9 @@ dnl Check for types
 AC_TYPE_PID_T
 AC_TYPE_SIZE_T
 AC_CHECK_TYPES([int64_t],,AC_MSG_ERROR([Type int64_t required but not found]))
-AC_CHECK_TYPES([uint64_t],,AC_MSG_ERROR([Type uint64_t required but not found]))
-AC_CHECK_TYPES([u_int64_t])
+AC_CHECK_TYPES([uint64_t],,
+               AC_CHECK_TYPES([u_int64_t],,
+                              AC_MSG_ERROR([Type uint64_t or u_int64_t required but not found])))
 AC_HEADER_TIME
 AC_STRUCT_TM