diff --git a/llvm/lib/Support/Parallel.cpp b/llvm/lib/Support/Parallel.cpp
--- a/llvm/lib/Support/Parallel.cpp
+++ b/llvm/lib/Support/Parallel.cpp
@@ -53,7 +53,9 @@
     Stop = true;
     Lock.unlock();
     Cond.notify_all();
-    // Wait for ~Latch.
+    // Explicitly wait threads to complete, otherwise the instance variables of
+    // this class can be prematurely destroyed.
+    Done.sync();
   }
 
   void add(std::function<void()> F) override {