diff --git a/llvm/include/llvm/ADT/StringSet.h b/llvm/include/llvm/ADT/StringSet.h
--- a/llvm/include/llvm/ADT/StringSet.h
+++ b/llvm/include/llvm/ADT/StringSet.h
@@ -36,7 +36,6 @@
     explicit StringSet(AllocatorTy A) : base(A) {}
 
     std::pair<typename base::iterator, bool> insert(StringRef Key) {
-      assert(!Key.empty());
       return base::insert(std::make_pair(Key, None));
     }
 
diff --git a/llvm/unittests/ADT/StringSetTest.cpp b/llvm/unittests/ADT/StringSetTest.cpp
--- a/llvm/unittests/ADT/StringSetTest.cpp
+++ b/llvm/unittests/ADT/StringSetTest.cpp
@@ -41,4 +41,15 @@
   Element->Destroy();
 }
 
+TEST_F(StringSetTest, EmptyString) {
+  // Verify that the empty string can by successfully inserted
+  StringSet<> Set;
+  size_t Count = Set.count("");
+  EXPECT_EQ(Count, 0UL);
+
+  Set.insert("");
+  Count = Set.count("");
+  EXPECT_EQ(Count, 1UL);
+}
+
 } // end anonymous namespace