diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -1103,4 +1103,20 @@
       export *
     }
   } // end experimental
+
+  module ext {
+    module hash_map {
+      // The use of __DEPRECATED requires textual inclusion.
+      textual header "ext/hash_map"
+      export *
+    }
+    module hash_set {
+      // The use of __DEPRECATED requires textual inclusion.
+      textual header "ext/hash_set"
+      export *
+    }
+    module __hash {
+      private header "ext/__hash"
+    }
+  } // end ext
 }