diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -132,6 +132,31 @@
 
 # Commands start here, listed alphabetically
 
+@command('abort',
+    dryrunopts, helpcategory=command.CATEGORY_CHANGE_MANAGEMENT,
+    helpbasic=True)
+def abort(ui, repo, **opts):
+    """abort an unfinished operation (EXPERIMENTAL)
+
+    Aborts a multistep operation like graft, histedit, rebase, merge,
+    and unshelve if they are in an unfinished state.
+
+    use --dry-run/-n to dry run the command.
+    A new operation can be added to this by registering the operation and
+    abort logic in the unfinishedstates list under statemod.
+    """
+    dryrun = opts.get(r'dry_run')
+    abortstate = cmdutil.getunfinishedstate(repo)
+    if not abortstate:
+        raise error.Abort(_('no operation in progress'))
+    if not abortstate.abortfunc:
+        raise error.Abort((_("%s in progress but does not support 'hg abort'") %
+                            (abortstate._opname)), hint=abortstate.hint())
+    if dryrun:
+        ui.status(_('%s in progress, will be aborted\n') % (abortstate._opname))
+        return
+    return abortstate.abortfunc(ui, repo)
+
 @command('add',
     walkopts + subrepoopts + dryrunopts,
     _('[OPTION]... [FILE]...'),
diff --git a/mercurial/state.py b/mercurial/state.py
--- a/mercurial/state.py
+++ b/mercurial/state.py
@@ -98,7 +98,8 @@
     """
 
     def __init__(self, opname, fname, clearable, allowcommit, reportonly,
-                 continueflag, stopflag, cmdmsg, cmdhint, statushint):
+                 continueflag, stopflag, cmdmsg, cmdhint, statushint,
+                 abortfunc):
         self._opname = opname
         self._fname = fname
         self._clearable = clearable
@@ -109,6 +110,7 @@
         self._cmdmsg = cmdmsg
         self._cmdhint = cmdhint
         self._statushint = statushint
+        self.abortfunc = abortfunc
 
     def statusmsg(self):
         """returns the hint message corresponding to the command for
@@ -157,7 +159,7 @@
 
 def addunfinished(opname, fname, clearable=False, allowcommit=False,
                   reportonly=False, continueflag=False, stopflag=False,
-                  cmdmsg="", cmdhint="", statushint=""):
+                  cmdmsg="", cmdhint="", statushint="", abortfunc=None):
     """this registers a new command or operation to unfinishedstates
     opname is the name the command or operation
     fname is the file name in which data should be stored in .hg directory.
@@ -181,10 +183,11 @@
     statushint is used to pass a different status message in case standard
     message of the format ('To continue:    hg cmdname --continue'
     'To abort:       hg cmdname --abort') is not desired
+    abortfunc stores the function required to abort an unfinished state.
     """
     statecheckobj = _statecheck(opname, fname, clearable, allowcommit,
                                 reportonly, continueflag, stopflag, cmdmsg,
-                                cmdhint, statushint)
+                                cmdhint, statushint, abortfunc)
     if opname == 'merge':
         _unfinishedstates.append(statecheckobj)
     else:
diff --git a/tests/test-blackbox.t b/tests/test-blackbox.t
--- a/tests/test-blackbox.t
+++ b/tests/test-blackbox.t
@@ -7,7 +7,7 @@
   > @command(b'crash', [], b'hg crash')
   > def crash(ui, *args, **kwargs):
   >     raise Exception("oops")
-  > @command(b'abort', [], b'hg abort')
+  > @command(b'abortcmd', [], b'hg abortcmd')
   > def abort(ui, *args, **kwargs):
   >     raise error.Abort(b"oops")
   > EOF
@@ -52,10 +52,10 @@
 
 abort exit code
   $ rm ./.hg/blackbox.log
-  $ hg abort 2> /dev/null
+  $ hg abortcmd 2> /dev/null
   [255]
   $ hg blackbox -l 2
-  1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000 (5000)> abort exited 255 after * seconds (glob)
+  1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000 (5000)> abortcmd exited 255 after * seconds (glob)
   1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000 (5000)> blackbox -l 2
 
 unhandled exception
diff --git a/tests/test-completion.t b/tests/test-completion.t
--- a/tests/test-completion.t
+++ b/tests/test-completion.t
@@ -1,5 +1,6 @@
 Show all commands except debug commands
   $ hg debugcomplete
+  abort
   add
   addremove
   annotate
@@ -59,6 +60,7 @@
 
 Show all commands that start with "a"
   $ hg debugcomplete a
+  abort
   add
   addremove
   annotate
@@ -235,6 +237,7 @@
 
 Show all commands + options
   $ hg debugcommands
+  abort: dry-run
   add: include, exclude, subrepos, dry-run
   addremove: similarity, subrepos, include, exclude, dry-run
   annotate: rev, follow, no-follow, text, user, file, date, number, changeset, line-number, skip, ignore-all-space, ignore-space-change, ignore-blank-lines, ignore-space-at-eol, include, exclude, template
diff --git a/tests/test-help.t b/tests/test-help.t
--- a/tests/test-help.t
+++ b/tests/test-help.t
@@ -402,6 +402,7 @@
   
   basic commands:
   
+   abort         abort an unfinished operation (EXPERIMENTAL)
    add           add the specified files on the next commit
    annotate, blame
                  show changeset information by line for each file
@@ -2353,6 +2354,13 @@
   <tr><td colspan="2"><h2><a name="main" href="#main">Main Commands</a></h2></td></tr>
   
   <tr><td>
+  <a href="/help/abort">
+  abort
+  </a>
+  </td><td>
+  abort an unfinished operation (EXPERIMENTAL)
+  </td></tr>
+  <tr><td>
   <a href="/help/add">
   add
   </a>
diff --git a/tests/test-hgweb-json.t b/tests/test-hgweb-json.t
--- a/tests/test-hgweb-json.t
+++ b/tests/test-hgweb-json.t
@@ -1875,6 +1875,10 @@
   {
     "earlycommands": [
       {
+        "summary": "abort an unfinished operation (EXPERIMENTAL)",
+        "topic": "abort"
+      },
+      {
         "summary": "add the specified files on the next commit",
         "topic": "add"
       },