diff --git a/hgext/remotefilelog/__init__.py b/hgext/remotefilelog/__init__.py
--- a/hgext/remotefilelog/__init__.py
+++ b/hgext/remotefilelog/__init__.py
@@ -230,6 +230,7 @@
 configitem(b'packs', b'maxchainlen', default=1000)
 
 configitem(b'devel', b'remotefilelog.ensurestart', default=False)
+configitem(b'devel', b'remotefilelog.bg-wait', default=False)
 
 #  default TTL limit is 30 days
 _defaultlimit = 60 * 60 * 24 * 30
diff --git a/hgext/remotefilelog/repack.py b/hgext/remotefilelog/repack.py
--- a/hgext/remotefilelog/repack.py
+++ b/hgext/remotefilelog/repack.py
@@ -48,7 +48,13 @@
         cmd.append(b'--packsonly')
     repo.ui.warn(msg)
     # We know this command will find a binary, so don't block on it starting.
-    procutil.runbgcommand(cmd, encoding.environ, ensurestart=ensurestart)
+    kwargs = {}
+    if repo.ui.configbool(b'devel', b'remotefilelog.bg-wait'):
+        kwargs['record_wait'] = repo.ui.atexit
+
+    procutil.runbgcommand(
+        cmd, encoding.environ, ensurestart=ensurestart, **kwargs
+    )
 
 
 def fullrepack(repo, options=None):
diff --git a/hgext/remotefilelog/shallowrepo.py b/hgext/remotefilelog/shallowrepo.py
--- a/hgext/remotefilelog/shallowrepo.py
+++ b/hgext/remotefilelog/shallowrepo.py
@@ -232,8 +232,12 @@
                 cmd += [b'-r', revs]
             # We know this command will find a binary, so don't block
             # on it starting.
+            kwargs = {}
+            if repo.ui.configbool(b'devel', b'remotefilelog.bg-wait'):
+                kwargs['record_wait'] = repo.ui.atexit
+
             procutil.runbgcommand(
-                cmd, encoding.environ, ensurestart=ensurestart
+                cmd, encoding.environ, ensurestart=ensurestart, **kwargs
             )
 
         def prefetch(self, revs, base=None, pats=None, opts=None):