diff --git a/tests/test-treemanifest-repack.t b/tests/test-treemanifest-repack.t
--- a/tests/test-treemanifest-repack.t
+++ b/tests/test-treemanifest-repack.t
@@ -276,3 +276,9 @@
   $ hg repack --incremental --config remotefilelog.data.generations=300,20
   $ ls_l .hg/cache/packs/manifests/ | grep datapack
   -r--r--r--     496 bc6c2ebb080844d7a227dacbc847a5b375ec620c.datapack
+
+- Test pruning the manifest cache using packs.maxpackfilecount
+  $ hg repack --incremental --config packs.maxpackfilecount=0
+  $ hg repack --incremental --config packs.maxpackfilecount=1
+  purging shared treemanifest pack cache (4 entries) -- too many files
+  $ ls_l .hg/cache/packs/manifests/
diff --git a/treemanifest/__init__.py b/treemanifest/__init__.py
--- a/treemanifest/__init__.py
+++ b/treemanifest/__init__.py
@@ -128,6 +128,7 @@
 import cstore
 
 import os
+import shutil
 import struct
 import time
 
@@ -263,6 +264,19 @@
     if not util.safehasattr(repo, 'connectionpool'):
         repo.connectionpool = connectionpool.connectionpool(repo)
 
+def _prunesharedpacks(repo, packpath):
+    """Wipe the packpath if it has too many packs in it"""
+    try:
+        numentries = len(os.listdir(packpath))
+        # Note this is based on file count, not pack count.
+        config = repo.ui.configint("packs", "maxpackfilecount")
+        if config and numentries > config:
+            repo.ui.warn("purging shared treemanifest pack cache (%d entries) "
+                         "-- too many files\n" % numentries)
+            shutil.rmtree(packpath, True)
+    except OSError:
+        pass
+
 def setuptreestores(repo, mfl):
     if repo.ui.configbool("treemanifest", "server"):
         packpath = repo.vfs.join('cache/packs/%s' % PACK_CATEGORY)
@@ -278,7 +292,7 @@
             historystore,
             revlogstore,
         )
-
+        _prunesharedpacks(repo, packpath)
         return
 
     usecdatapack = repo.ui.configbool('remotefilelog', 'fastdatapack')
@@ -286,6 +300,7 @@
     if not util.safehasattr(repo, 'name'):
         repo.name = repo.ui.config('remotefilelog', 'reponame')
     packpath = shallowutil.getcachepackpath(repo, PACK_CATEGORY)
+    _prunesharedpacks(repo, packpath)
 
     localpackpath = shallowutil.getlocalpackpath(repo.svfs.vfs.base,
                                                  PACK_CATEGORY)