diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -795,6 +795,7 @@
 def makefilestorage(requirements, features, **kwargs):
     """Produce a type conforming to ``ilocalrepositoryfilestorage``."""
     features.add(repository.REPO_FEATURE_REVLOG_FILE_STORAGE)
+    features.add(repository.REPO_FEATURE_STREAM_CLONE)
 
     if repository.NARROW_REQUIREMENT in requirements:
         return revlognarrowfilestorage
diff --git a/mercurial/repository.py b/mercurial/repository.py
--- a/mercurial/repository.py
+++ b/mercurial/repository.py
@@ -27,6 +27,8 @@
 REPO_FEATURE_SHARED_STORAGE = b'sharedstore'
 # LFS supported for backing file storage.
 REPO_FEATURE_LFS = b'lfs'
+# Repository supports being stream cloned.
+REPO_FEATURE_STREAM_CLONE = b'streamclone'
 
 class ipeerconnection(interfaceutil.Interface):
     """Represents a "connection" to a repository.