=== modified file 'lisp/ChangeLog'
--- lisp/ChangeLog	2012-10-12 16:19:16 +0000
+++ lisp/ChangeLog	2012-10-12 18:03:45 +0000
@@ -1,5 +1,10 @@
 2012-10-12  Jambunathan K  <kjambunathan@gmail.com>
 
+	* hi-lock.el (hi-lock-unface-buffer): With prefix arg, unhighlight
+	all hi-lock patterns in buffer.
+
+2012-10-12  Jambunathan K  <kjambunathan@gmail.com>
+
 	* hi-lock.el (hi-lock-unface-buffer): Prompt user with useful
 	defaults.  Specifically, if cursor is on an highlighted text,
 	offer a regexp that matches that text as the default.  Update

=== modified file 'lisp/hi-lock.el'
--- lisp/hi-lock.el	2012-10-12 16:19:16 +0000
+++ lisp/hi-lock.el	2012-10-12 17:35:34 +0000
@@ -491,17 +491,18 @@ updated as you type."
 ;;;###autoload
 (defalias 'unhighlight-regexp 'hi-lock-unface-buffer)
 ;;;###autoload
-(defun hi-lock-unface-buffer (regexp)
+(defun hi-lock-unface-buffer (regexp &optional prefix-arg)
   "Remove highlighting of each match to REGEXP set by hi-lock.
-Interactively, prompt for REGEXP.  If the cursor is on a
-previously highlighted text and if the associated regexp can be
-inferred via simple heuristics, offer that regexp as default.
-Otherwise, prompt for REGEXP with completion and limit the
-choices to only those regexps used previously with hi-lock
-commands.
+Interactively, when PREFIX-ARG is non-nil, unhighlight all
+highlighted text in current buffer.  When PREFIX-ARG is nil,
+prompt for REGEXP.  If the cursor is on a previously highlighted
+text and if the associated regexp can be inferred via simple
+heuristics, offer that regexp as default.  Otherwise, prompt for
+REGEXP with completion and limit the choices to only those
+regexps used previously with hi-lock commands.
 
-If this command is invoked via menu, make no attempt to infer
-REGEXP from text at point."
+If this command is invoked via menu, pop-up a list of currently
+highlighted patterns."
   (interactive
    (if (and (display-popup-menus-p)
 	    (listp last-nonmenu-event)
@@ -570,18 +571,22 @@ REGEXP from text at point."
 		      ;; a reasonable default.
 		      (caar candidate-hi-lock-patterns))))))
        (list
+	(and (not current-prefix-arg)
 	(completing-read "Regexp to unhighlight: "
 			 (or candidate-hi-lock-patterns
 			     hi-lock-interactive-patterns)
-			 nil t default-regexp)))))
-  (let ((keyword (assoc regexp hi-lock-interactive-patterns)))
+			      nil t default-regexp))
+	current-prefix-arg))))
+  (dolist (re (if (not prefix-arg) (list regexp)
+		(mapcar #'car hi-lock-interactive-patterns)))
+    (let ((keyword (assoc re hi-lock-interactive-patterns)))
     (when keyword
       (font-lock-remove-keywords nil (list keyword))
       (setq hi-lock-interactive-patterns
             (delq keyword hi-lock-interactive-patterns))
       (remove-overlays
-       nil nil 'hi-lock-overlay-regexp (hi-lock-string-serialize regexp))
-      (when font-lock-fontified (font-lock-fontify-buffer)))))
+	 nil nil 'hi-lock-overlay-regexp (hi-lock-string-serialize re))
+	(when font-lock-fontified (font-lock-fontify-buffer))))))
 
 ;;;###autoload
 (defun hi-lock-write-interactive-patterns ()