diff --git a/lib/CodeGen/PBQP.cpp b/lib/CodeGen/PBQP.cpp
index 6b2110583fe..d4d1098bb87 100644
--- a/lib/CodeGen/PBQP.cpp
+++ b/lib/CodeGen/PBQP.cpp
@@ -18,6 +18,7 @@
 #include <cstring>
 
 #include "PBQP.h"
+#include "llvm/Config/alloca.h"
 
 namespace llvm {