diff --git a/llvm/include/llvm/Support/Process.h b/llvm/include/llvm/Support/Process.h
--- a/llvm/include/llvm/Support/Process.h
+++ b/llvm/include/llvm/Support/Process.h
@@ -216,6 +216,10 @@
   /// Use \arg NoCleanup for calling _exit() instead of exit().
   LLVM_ATTRIBUTE_NORETURN
   static void Exit(int RetCode, bool NoCleanup = false);
+
+private:
+  LLVM_ATTRIBUTE_NORETURN
+  static void ExitNoCleanup(int RetCode);
 };
 
 }
diff --git a/llvm/lib/Support/Process.cpp b/llvm/lib/Support/Process.cpp
--- a/llvm/lib/Support/Process.cpp
+++ b/llvm/lib/Support/Process.cpp
@@ -98,7 +98,7 @@
     CRC->HandleExit(RetCode);
 
   if (NoCleanup)
-    _Exit(RetCode);
+    ExitNoCleanup(RetCode);
   else
     ::exit(RetCode);
 }
diff --git a/llvm/lib/Support/Unix/Process.inc b/llvm/lib/Support/Unix/Process.inc
--- a/llvm/lib/Support/Unix/Process.inc
+++ b/llvm/lib/Support/Unix/Process.inc
@@ -460,3 +460,6 @@
   return ::rand();
 #endif
 }
+
+LLVM_ATTRIBUTE_NORETURN
+void Process::ExitNoCleanup(int RetCode) { _Exit(RetCode); }
diff --git a/llvm/lib/Support/Windows/Process.inc b/llvm/lib/Support/Windows/Process.inc
--- a/llvm/lib/Support/Windows/Process.inc
+++ b/llvm/lib/Support/Windows/Process.inc
@@ -503,3 +503,9 @@
   // Windows 8 is version 6.2, service pack 0.
   return GetWindowsOSVersion() >= llvm::VersionTuple(6, 2, 0, 0);
 }
+
+LLVM_ATTRIBUTE_NORETURN
+void Process::ExitNoCleanup(int RetCode) {
+  TerminateProcess(GetCurrentProcess(), RetCode);
+  llvm_unreachable("TerminateProcess doesn't return");
+}