diff --git a/llvm/include/llvm/ADT/StringMap.h b/llvm/include/llvm/ADT/StringMap.h
index 453d91349e358..daaf82654e094 100644
--- a/llvm/include/llvm/ADT/StringMap.h
+++ b/llvm/include/llvm/ADT/StringMap.h
@@ -291,8 +291,10 @@ class LLVM_ALLOCATORHOLDER_EMPTYBASE StringMap
       if (FindInRHS == RHS.end())
         return false;
 
-      if (!(KeyValue.getValue() == FindInRHS->getValue()))
-        return false;
+      if constexpr (!std::is_same_v<ValueTy, std::nullopt_t>) {
+        if (!(KeyValue.getValue() == FindInRHS->getValue()))
+          return false;
+      }
     }
 
     return true;
diff --git a/llvm/unittests/ADT/StringSetTest.cpp b/llvm/unittests/ADT/StringSetTest.cpp
index e3703f6f01508..a804c1f17d1ce 100644
--- a/llvm/unittests/ADT/StringSetTest.cpp
+++ b/llvm/unittests/ADT/StringSetTest.cpp
@@ -73,4 +73,12 @@ TEST_F(StringSetTest, Contains) {
   EXPECT_FALSE(Set.contains("test"));
 }
 
+TEST_F(StringSetTest, Equal) {
+  StringSet<> A = {"A"};
+  StringSet<> B = {"B"};
+  ASSERT_TRUE(A != B);
+  ASSERT_FALSE(A == B);
+  ASSERT_TRUE(A == A);
+}
+
 } // end anonymous namespace