This should do the trick. Just add this to your .emacs

(defun save-all-and-quit ()
  (interactive)
  (save-some-buffers t)
  (kill-emacs))
(global-set-key (kbd "S-; x") 'save-all-and-quit)

This is considering you want to save all buffers without prompting interactively for yes or no for all the unsaved buffers.

This should do the trick. Just add this to your .emacs and bind it to a key and you're done

(defun save-all-and-quit ()
  (interactive)
  (save-some-buffers t)
  (kill-emacs))

This is considering you want to save all buffers without prompting interactively for yes or no for all the unsaved buffers.