diff --git a/clang-tools-extra/clangd/IncludeCleaner.cpp b/clang-tools-extra/clangd/IncludeCleaner.cpp
--- a/clang-tools-extra/clangd/IncludeCleaner.cpp
+++ b/clang-tools-extra/clangd/IncludeCleaner.cpp
@@ -133,6 +133,11 @@
     return true;
   }
 
+  bool VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
+    add(D->getNominatedNamespace());
+    return true;
+  }
+
   // Enums may be usefully forward-declared as *complete* types by specifying
   // an underlying type. In this case, the definition should see the declaration
   // so they can be checked for compatibility.
diff --git a/clang-tools-extra/clangd/unittests/IncludeCleanerTests.cpp b/clang-tools-extra/clangd/unittests/IncludeCleanerTests.cpp
--- a/clang-tools-extra/clangd/unittests/IncludeCleanerTests.cpp
+++ b/clang-tools-extra/clangd/unittests/IncludeCleanerTests.cpp
@@ -77,7 +77,7 @@
           "using ns::foo;",
       },
       {
-          "namespace ns { void foo(); void foo() {}; }",
+          "namespace ^ns { void foo(); void foo() {}; }",
           "using namespace ns;",
       },
       {