--- a/mercurial/subrepo.py	Mon Feb 04 21:31:18 2019 -0800
+++ b/mercurial/subrepo.py	Tue Feb 05 09:43:34 2019 -0800
@@ -1824,15 +1824,15 @@
         if not opts.get(r'no_backup'):
             status = self.status(None)
             names = status.modified
-            origvfs = scmutil.getorigvfs(self.ui, self._subparent)
-            if origvfs is None:
-                origvfs = self.wvfs
             for name in names:
-                bakname = scmutil.origpath(self.ui, self._subparent, name)
+                # backuppath() expects a path relative to the parent repo (the
+                # repo that ui.origbackuppath is relative to)
+                parentname = os.path.join(self._path, name)
+                bakname = scmutil.backuppath(self.ui, self._subparent,
+                                             parentname)
                 self.ui.note(_('saving current version of %s as %s\n') %
                         (name, os.path.relpath(bakname)))
-                name = self.wvfs.join(name)
-                origvfs.rename(name, bakname)
+                util.rename(self.wvfs.join(name), bakname)
 
         if not opts.get(r'dry_run'):
             self.get(substate, overwrite=True)

--- a/tests/test-subrepo-git.t	Mon Feb 04 21:31:18 2019 -0800
+++ b/tests/test-subrepo-git.t	Tue Feb 05 09:43:34 2019 -0800
@@ -924,9 +924,9 @@
   $ echo 'bloop' > s/foobar
   $ hg revert --all --verbose --config 'ui.origbackuppath=.hg/origbackups'
   reverting subrepo ../gitroot
-  creating directory: $TESTTMP/tc/.hg/origbackups
-  saving current version of foobar as .hg/origbackups/foobar
-  $ ls .hg/origbackups
+  creating directory: $TESTTMP/tc/.hg/origbackups/s
+  saving current version of foobar as .hg/origbackups/s/foobar
+  $ ls .hg/origbackups/s
   foobar
   $ rm -rf .hg/origbackups