diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -4529,10 +4529,16 @@
     """
 
     opts = pycompat.byteskwargs(opts)
+    confirm = ui.configbool('commands', 'resolve.confirm')
     flaglist = 'all mark unmark list no_status'.split()
     all, mark, unmark, show, nostatus = \
         [opts.get(o) for o in flaglist]
 
+    if all and confirm:
+        if ui.promptchoice(_(b're-merge all unresolved files (yn)?'
+                             b'$$ &Yes $$ &No')):
+            raise error.Abort(_('user quit'))
+
     if (show and (mark or unmark)) or (mark and unmark):
         raise error.Abort(_("too many options specified"))
     if pats and all:
diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -190,6 +190,9 @@
 coreconfigitem('commands', 'grep.all-files',
     default=False,
 )
+coreconfigitem('commands', 'resolve.confirm',
+    default=False,
+)
 coreconfigitem('commands', 'show.aliasprefix',
     default=list,
 )
diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -438,6 +438,11 @@
 ``commands``
 ------------
 
+``resolve.confirm``
+    Confirm before re-merging all unresolved files when running
+    :hg:`resolve --all`.
+    (default: False)
+
 ``status.relative``
     Make paths in :hg:`status` output relative to the current directory.
     (default: False)
diff --git a/tests/test-resolve.t b/tests/test-resolve.t
--- a/tests/test-resolve.t
+++ b/tests/test-resolve.t
@@ -423,3 +423,92 @@
   R file2
 
   $ cd ..
+
+======================================================
+Test 'hg resolve' confirm config option functionality |
+======================================================
+  $ cat >> $HGRCPATH << EOF
+  > [extensions]
+  > rebase=
+  > EOF
+
+  $ hg init repo2
+  $ cd repo2
+
+  $ echo boss > boss
+  $ hg ci -Am "add boss"
+  adding boss
+
+  $ for emp in emp1 emp2 emp3; do echo work > $emp; done;
+  $ hg ci -Aqm "added emp1 emp2 emp3"
+
+  $ hg up 0
+  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
+
+  $ for emp in emp1 emp2 emp3; do echo nowork > $emp; done;
+  $ hg ci -Aqm "added lazy emp1 emp2 emp3"
+
+  $ hg log -GT "{rev} {node|short} {firstline(desc)}\n"
+  @  2 0acfd4a49af0 added lazy emp1 emp2 emp3
+  |
+  | o  1 f30f98a8181f added emp1 emp2 emp3
+  |/
+  o  0 88660038d466 add boss
+  
+  $ hg rebase -s 1 -d 2
+  rebasing 1:f30f98a8181f "added emp1 emp2 emp3"
+  merging emp1
+  merging emp2
+  merging emp3
+  warning: conflicts while merging emp1! (edit, then use 'hg resolve --mark')
+  warning: conflicts while merging emp2! (edit, then use 'hg resolve --mark')
+  warning: conflicts while merging emp3! (edit, then use 'hg resolve --mark')
+  unresolved conflicts (see hg resolve, then hg rebase --continue)
+  [1]
+
+Test when commands.resolve.confirm config option is not set:
+===========================================================
+  $ hg resolve --all
+  merging emp1
+  merging emp2
+  merging emp3
+  warning: conflicts while merging emp1! (edit, then use 'hg resolve --mark')
+  warning: conflicts while merging emp2! (edit, then use 'hg resolve --mark')
+  warning: conflicts while merging emp3! (edit, then use 'hg resolve --mark')
+  [1]
+
+Test when config option is set:
+==============================
+  $ cat >> $HGRCPATH << EOF
+  > [ui]
+  > interactive = True
+  > [commands]
+  > resolve.confirm = True
+  > EOF
+
+  $ hg resolve
+  abort: no files or directories specified
+  (use --all to re-merge all unresolved files)
+  [255]
+  $ hg resolve --all << EOF
+  > n
+  > EOF
+  re-merge all unresolved files (yn)? n
+  abort: user quit
+  [255]
+
+  $ hg resolve --all << EOF
+  > y
+  > EOF
+  re-merge all unresolved files (yn)? y
+  merging emp1
+  merging emp2
+  merging emp3
+  warning: conflicts while merging emp1! (edit, then use 'hg resolve --mark')
+  warning: conflicts while merging emp2! (edit, then use 'hg resolve --mark')
+  warning: conflicts while merging emp3! (edit, then use 'hg resolve --mark')
+  [1]
+
+  $ hg rebase --abort
+  rebase aborted
+  $ cd ..