--- a/hgext/largefiles/overrides.py	Thu Dec 21 13:53:26 2017 +0100
+++ b/hgext/largefiles/overrides.py	Thu Dec 21 13:57:57 2017 +0100
@@ -1479,3 +1479,14 @@
     if 'largefiles' in repo.requirements:
         reqs.add('largefiles')
     return reqs
+
+_lfscheme = 'largefile://'
+def openlargefile(orig, ui, url_, data=None):
+    if url_.startswith(_lfscheme):
+        if data:
+            msg = "cannot use data on a 'largefile://' url"
+            raise error.ProgrammingError(msg)
+        lfid = url_[len(_lfscheme):]
+        return storefactory.getlfile(ui, lfid)
+    else:
+        return orig(ui, url_, data=data)

--- a/hgext/largefiles/remotestore.py	Thu Dec 21 13:53:26 2017 +0100
+++ b/hgext/largefiles/remotestore.py	Thu Dec 21 13:57:57 2017 +0100
@@ -27,7 +27,9 @@
     '''a largefile store accessed over a network'''
     def __init__(self, ui, repo, url):
         super(remotestore, self).__init__(ui, repo, url)
-        self._lstore = localstore.localstore(self.ui, self.repo, self.repo)
+        self._lstore = None
+        if repo is not None:
+            self._lstore = localstore.localstore(self.ui, self.repo, self.repo)
 
     def put(self, source, hash):
         if self.sendfile(source, hash):

--- a/hgext/largefiles/storefactory.py	Thu Dec 21 13:53:26 2017 +0100
+++ b/hgext/largefiles/storefactory.py	Thu Dec 21 13:57:57 2017 +0100
@@ -22,8 +22,9 @@
 # During clone this function is passed the src's ui object
 # but it needs the dest's ui object so it can read out of
 # the config file. Use repo.ui instead.
-def openstore(repo, remote=None, put=False):
-    ui = repo.ui
+def openstore(repo=None, remote=None, put=False, ui=None):
+    if ui is None:
+        ui = repo.ui
 
     if not remote:
         lfpullsource = getattr(repo, 'lfpullsource', None)
@@ -37,12 +38,16 @@
         # ui.expandpath() leaves 'default-push' and 'default' alone if
         # they cannot be expanded: fallback to the empty string,
         # meaning the current directory.
-        if path == 'default-push' or path == 'default':
+        if repo is None:
+            path = ui.expandpath('default')
+            path, _branches = hg.parseurl(path)
+            remote = hg.peer(repo or ui, {}, path)
+        elif path == 'default-push' or path == 'default':
             path = ''
             remote = repo
         else:
             path, _branches = hg.parseurl(path)
-            remote = hg.peer(repo, {}, path)
+            remote = hg.peer(repo or ui, {}, path)
 
     # The path could be a scheme so use Mercurial's normal functionality
     # to resolve the scheme to a repository and use its path
@@ -76,3 +81,6 @@
     }
 
 _scheme_re = re.compile(r'^([a-zA-Z0-9+-.]+)://')
+
+def getlfile(ui, hash):
+    return util.chunkbuffer(openstore(ui=ui)._get(hash))

--- a/hgext/largefiles/uisetup.py	Thu Dec 21 13:53:26 2017 +0100
+++ b/hgext/largefiles/uisetup.py	Thu Dec 21 13:57:57 2017 +0100
@@ -31,6 +31,7 @@
     sshpeer,
     subrepo,
     upgrade,
+    url,
     wireproto,
 )
 
@@ -160,6 +161,9 @@
     extensions.wrapfunction(scmutil, 'marktouched',
                             overrides.scmutilmarktouched)
 
+    extensions.wrapfunction(url, 'open',
+                            overrides.openlargefile)
+
     # create the new wireproto commands ...
     wireproto.commands['putlfile'] = (proto.putlfile, 'sha')
     wireproto.commands['getlfile'] = (proto.getlfile, 'sha')

--- a/tests/test-url-download.t	Thu Dec 21 13:53:26 2017 +0100
+++ b/tests/test-url-download.t	Thu Dec 21 13:57:57 2017 +0100
@@ -34,3 +34,21 @@
   $ hg debugdownload ./null.txt
   1 0000000000000000000000000000000000000000
 
+Test largefile URL
+------------------
+
+  $ cat << EOF >> $HGRCPATH
+  > [extensions]
+  > largefiles=
+  > EOF
+
+  $ killdaemons.py
+  $ rm -f error.log hg1.pid
+  $ hg serve -R server -p $HGPORT -d --pid-file=hg1.pid -E error.log
+  $ cat hg1.pid >> $DAEMON_PIDS
+
+  $ hg -R server debuglfput null.txt
+  a57b57b39ee4dc3da1e03526596007f480ecdbe8
+
+  $ hg --traceback debugdownload "largefile://a57b57b39ee4dc3da1e03526596007f480ecdbe8" --config paths.default=http://localhost:$HGPORT/
+  1 0000000000000000000000000000000000000000