--- a/include/lldb/Utility/TaskPool.h	2017-06-02 00:40:33.193667646 -0700
+++ b/include/lldb/Utility/TaskPool.h	2017-06-02 00:41:23.103642236 -0700
@@ -28,6 +28,7 @@
 
 #include <cassert>
 #include <cstdint>
+#include <functional>
 #include <future>
 #include <list>
 #include <queue>