diff --git a/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp b/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
--- a/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/RemoveUsingNamespace.cpp
@@ -155,6 +155,13 @@
             if (!visibleContext(T->getDeclContext())
                      ->Equals(TargetDirective->getNominatedNamespace()))
               return;
+            // Avoid adding qualifiers before operators, e.g.
+            //   using namespace std;
+            //   cout << "foo"; // Must not changed to std::cout std:: << "foo"
+            // FIXME: User-defined literals are not handled
+            if (T->isInIdentifierNamespace(
+                    Decl::IdentifierNamespace::IDNS_NonMemberOperator))
+              return;
           }
           SourceLocation Loc = Ref.NameLoc;
           if (Loc.isMacroID()) {
diff --git a/clang-tools-extra/clangd/unittests/tweaks/RemoveUsingNamespaceTests.cpp b/clang-tools-extra/clangd/unittests/tweaks/RemoveUsingNamespaceTests.cpp
--- a/clang-tools-extra/clangd/unittests/tweaks/RemoveUsingNamespaceTests.cpp
+++ b/clang-tools-extra/clangd/unittests/tweaks/RemoveUsingNamespaceTests.cpp
@@ -226,7 +226,30 @@
       int main() {
         std::vector V;
       }
-    )cpp"}};
+    )cpp"},
+      {// Does not qualify operators declared in a non-class context
+       R"cpp(
+      namespace ns {
+      struct Foo {};
+      void operator+(const Foo &, int) {}
+      }
+      using namespace n^s;
+      int main() {
+        Foo foo;
+        foo + 10;
+      }
+      )cpp",
+       R"cpp(
+      namespace ns {
+      struct Foo {};
+      void operator+(const Foo &, int) {}
+      }
+      
+      int main() {
+        ns::Foo foo;
+        foo + 10;
+      }
+      )cpp"}};
   for (auto C : Cases)
     EXPECT_EQ(C.second, apply(C.first)) << C.first;
 }