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 +74,22 @@
 ;;;###autoload
 (add-to-list 'auto-mode-alist (cons "\\.mlir\\'" 'mlir-mode))
 
+;; Set default value of opt-tool to use as mlir-opt.
+(defcustom mlir-opt "mlir-opt"
+  "Commandline MLIR opt tool to use."
+  :type 'string)
+
+;; Enable reading/writing .mlirbc files.
+(require 'jka-compr)
+(add-to-list 'jka-compr-compression-info-list
+  (vector "\\.mlirbc\\'"
+   "mlir-to-bytecode" mlir-opt (vector "--emit-bytecode" "-o" "-" "-")
+   "mlir-bytecode-to-text" mlir-opt ()
+   nil nil "ML\357R"))
+(jka-compr-update)
+(auto-compression-mode t)
+(add-to-list 'auto-mode-alist (cons "\\.mlirbc\\'" 'mlir-mode))
+
 (provide 'mlir-mode)
 
 ;;; mlir-mode.el ends here