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
@@ -155,12 +155,14 @@
             if (!visibleContext(T->getDeclContext())
                      ->Equals(TargetDirective->getNominatedNamespace()))
               return;
-            // Avoid adding qualifiers before operators, e.g.
+            // Avoid adding qualifiers before operators
+            // and user-defined literals, e.g.
             //   using namespace std;
+            //   auto s = "foo"s; // Must not changed to auto s = "foo" std::s;
             //   cout << "foo"; // Must not changed to std::cout std:: << "foo"
-            // FIXME: User-defined literals are not handled
-            if (T->isInIdentifierNamespace(
-                    Decl::IdentifierNamespace::IDNS_NonMemberOperator))
+            if (auto kind = T->getDeclName().getNameKind();
+                kind == DeclarationName::NameKind::CXXOperatorName ||
+                kind == DeclarationName::NameKind::CXXLiteralOperatorName)
               return;
           }
           SourceLocation Loc = Ref.NameLoc;
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
@@ -249,6 +249,21 @@
         ns::Foo foo;
         foo + 10;
       }
+    )cpp"},
+      {// Does qualify user-defined literals
+       R"cpp(
+      namespace ns {
+      long double operator "" _w(long double);
+      }
+      using namespace n^s;
+      int main() { 1.5_w; }
+    )cpp",
+       R"cpp(
+      namespace ns {
+      long double operator "" _w(long double);
+      }
+      
+      int main() { 1.5_w; }
     )cpp"}};
   for (auto C : Cases)
     EXPECT_EQ(C.second, apply(C.first)) << C.first;