diff --git a/runtime/doc/change.txt b/runtime/doc/change.txt
--- a/runtime/doc/change.txt
+++ b/runtime/doc/change.txt
@@ -635,6 +635,12 @@
 			compiled without the |+insert_expand| feature}
 	    CTRL-Y  to scroll the screen down {not in Vi, not available when
 			compiled without the |+insert_expand| feature}
+            'Q'     to quit substituting for all invocations of :s in a :g
+                        command (only when inside a :g command) {not in Vi}
+            'A'     to substitute all matches for all invocations of :s
+                        in a :g command (only when inside a :g command) {not
+                        in Vi}
+            '?'     to display a small help banner {not in Vi}
 	If the 'edcompatible' option is on, Vim remembers the [c] flag and
 	toggles it each time you use it, but resets it when you give a new
 	search pattern.
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -4384,6 +4384,7 @@
     {
 	sub_nsubs = 0;
 	sub_nlines = 0;
+	global_stop_ask = FALSE;
     }
     start_nsubs = sub_nsubs;
 
@@ -4811,7 +4812,7 @@
 		    /*
 		     * Loop until 'y', 'n', 'q', CTRL-E or CTRL-Y typed.
 		     */
-		    while (do_ask)
+		    while (do_ask && !global_stop_ask)
 		    {
 			if (exmode_active)
 			{
@@ -4903,12 +4904,19 @@
 			    msg_starthere();
 			    i = msg_scroll;
 			    msg_scroll = 0;		/* truncate msg when
-							   needed */
+							needed */
 			    msg_no_more = TRUE;
 			    /* write message same highlighting as for
-			     * wait_return */
+			    * wait_return */
 			    smsg_attr(hl_attr(HLF_R),
-				    (char_u *)_("replace with %s (y/n/a/q/l/^E/^Y)?"), sub);
+				(char_u *)_("replace with %s (y/n/a/q/l%s%s/?)?"), sub,
+#ifdef FEAT_INS_EXPAND
+				"/^E/^Y",
+#else
+				"",
+#endif
+				(global_busy ? "/Q/A" : "")
+				);
 			    msg_no_more = FALSE;
 			    msg_scroll = i;
 			    showruler(TRUE);
@@ -4933,14 +4941,43 @@
 			    if (orig_line != NULL)
 				ml_replace(lnum, orig_line, FALSE);
 			}
+			if (typed == '?')
+			{
+			    int need_wait_return_save = need_wait_return;
+			    int no_wait_return_save = no_wait_return;
+
+			    mgs_starthere();
+			    MSG_PUTS((char_u *)"y\t- substitute this match\n");
+			    MSG_PUTS((char_u *)"n\t- skip this match\n");
+			    MSG_PUTS((char_u *)"l\t- substitute this match and quit\n");
+			    MSG_PUTS((char_u *)"a\t- substitute this match and all remaining\n");
+			    MSG_PUTS((char_u *)"q\t- quit\n");
+#ifdef FEAT_INS_EXPAND
+			    MSG_PUTS((char_u *)"<C-E>\t- scroll screen up\n");
+			    MSG_PUTS((char_u *)"<C-Y>\t- scroll screen down\n");
+#endif
+			    if (global_busy)
+			    {
+				MSG_PUTS((char_u *)"A\t- substitute all matches globally (on all :g matches)\n");
+				MSG_PUTS((char_u *)"Q\t- quit globally (on all :g matches)\n");
+			    }
+			    need_wait_return = TRUE;
+			    no_wait_return = FALSE;
+			    msg_end();
+			    need_wait_return = need_wait_return_save;
+			    no_wait_return   = no_wait_return_save;
+			}
 
 			need_wait_return = FALSE; /* no hit-return prompt */
 			if (typed == 'q' || typed == ESC || typed == Ctrl_C
+                                || (typed == 'Q' && global_busy)
 #ifdef UNIX
 				|| typed == intr_char
 #endif
 				)
 			{
+                            if (typed == 'Q')
+                                ++global_busy; /* break :g command */
 			    got_quit = TRUE;
 			    break;
 			}
@@ -4955,6 +4992,12 @@
 			    line2 = lnum;
 			    break;
 			}
+			if (typed == 'A' && global_busy)
+			{
+			    if (global_busy)
+				global_stop_ask = TRUE;
+			    break;
+			}
 			if (typed == 'a')
 			{
 			    do_ask = FALSE;
@@ -5448,6 +5491,7 @@
 	type = *eap->cmd;
     cmd = eap->arg;
     which_pat = RE_LAST;	    /* default: use last used regexp */
+    global_stop_ask = FALSE;	    /* for a :s command with c flag */
 
     /*
      * undocumented vi feature:
diff --git a/src/globals.h b/src/globals.h
--- a/src/globals.h
+++ b/src/globals.h
@@ -1197,6 +1197,7 @@
  */
 EXTERN long	sub_nsubs;	/* total number of substitutions */
 EXTERN linenr_T	sub_nlines;	/* total number of lines changed */
+EXTERN int	global_stop_ask INIT(= FALSE);	/* c flag for :s command */
 
 /* table to store parsed 'wildmode' */
 EXTERN char_u	wim_flags[4];