diff --git a/unittests/Basic/FrozenMultiMapTest.cpp b/unittests/Basic/FrozenMultiMapTest.cpp
index 23637f79018..0424b029de8 100644
--- a/unittests/Basic/FrozenMultiMapTest.cpp
+++ b/unittests/Basic/FrozenMultiMapTest.cpp
@@ -25,6 +25,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 #include "gtest/gtest.h"
+#include <chrono>
 #include <map>
 #include <random>
 #include <set>