--- a/lldb/include/lldb/Utility/TaskPool.h	2016-09-06 16:57:50.000000000 -0400
+++ b/lldb/include/lldb/Utility/TaskPool.h	2017-08-29 16:29:41.448584015 -0400
@@ -28,6 +28,7 @@
 
 #include <cassert>
 #include <cstdint>
+#include <functional>
 #include <future>
 #include <list>
 #include <queue>