--- lisp/simple.el
+++ lisp/simple.el
@@ -3455,7 +3455,11 @@
 old mark position on local mark ring.  Also push the old mark on
 global mark ring, if the previous mark was set in another buffer.
 
-Immediately repeating this command activates `transient-mark-mode' temporarily.
+When `transient-mark-mode' is off, immediately repeating this command 
+activates `transient-mark-mode' temporarily, immediately repeating it 
+again  deactivates that temporary activation and the mark.  When 
+`transient-mark-mode' is on, immediately repeating this command
+deactivates the mark (mark having been activated by the preceding).
 
 With prefix argument \(e.g., \\[universal-argument] \\[set-mark-command]\), \
 jump to the mark, and set the mark from
@@ -3474,6 +3478,7 @@
 Novice Emacs Lisp programmers often try to use the mark for the wrong
 purposes.  See the documentation of `set-mark' for more information."
   (interactive "P")
+  (let ((last-transient-mark-mode transient-mark-mode))
   (if (eq transient-mark-mode 'lambda)
       (setq transient-mark-mode nil))
   (cond
@@ -3496,11 +3501,20 @@
     (setq this-command 'pop-to-mark-command)
     (pop-to-mark-command))
    ((and (eq last-command 'set-mark-command)
+	 mark-active (eq 'lambda last-transient-mark-mode))
+    (deactivate-mark)
+    (setq transient-mark-mode nil)
+    (message "Disabled temporarily enabled Transient-mark-mode"))
+   ((and (eq last-command 'set-mark-command)
 	 mark-active (null transient-mark-mode))
     (setq transient-mark-mode 'lambda)
     (message "Transient-mark-mode temporarily enabled"))
+   ((and (eq last-command 'set-mark-command)
+         mark-active (eq t transient-mark-mode))
+    (deactivate-mark)
+    (message "Mark deactivated"))
    (t
-    (push-mark-command nil))))
+    (push-mark-command nil)))))
 
 (defun push-mark (&optional location nomsg activate)
   "Set mark at LOCATION (point, by default) and push old mark on mark ring.