diff --git a/mlir/utils/emacs/mlir-mode.el b/mlir/utils/emacs/mlir-mode.el
--- a/mlir/utils/emacs/mlir-mode.el
+++ b/mlir/utils/emacs/mlir-mode.el
@@ -74,6 +74,11 @@
 ;;;###autoload
 (add-to-list 'auto-mode-alist (cons "\\.mlir\\'" 'mlir-mode))
 
+(defgroup mlir nil
+  "Major mode for editing MLIR source files."
+  :group 'languages
+  :prefix "mlir-")
+
 ;; Set default value of opt-tool to use as mlir-opt.
 (defcustom mlir-opt "mlir-opt"
   "Commandline MLIR opt tool to use."