diff --git a/clang-tools-extra/clangd/Shutdown.cpp b/clang-tools-extra/clangd/Shutdown.cpp
--- a/clang-tools-extra/clangd/Shutdown.cpp
+++ b/clang-tools-extra/clangd/Shutdown.cpp
@@ -9,6 +9,7 @@
 #include "Shutdown.h"
 
 #include <atomic>
+#include <cstdlib>
 #include <thread>
 
 namespace clang {