diff --git a/llvm/lib/Support/Windows/Signals.inc b/llvm/lib/Support/Windows/Signals.inc
--- a/llvm/lib/Support/Windows/Signals.inc
+++ b/llvm/lib/Support/Windows/Signals.inc
@@ -731,6 +731,11 @@
 /// otherwise.
 static std::error_code WINAPI
 WriteWindowsDumpFile(PMINIDUMP_EXCEPTION_INFORMATION ExceptionInfo) {
+  struct ScopedCriticalSection {
+    ScopedCriticalSection() { EnterCriticalSection(&CriticalSection); }
+    ~ScopedCriticalSection() { LeaveCriticalSection(&CriticalSection); }
+  } SCS;
+
   using namespace llvm;
   using namespace llvm::sys;