diff --git a/remotefilelog/__init__.py b/remotefilelog/__init__.py
--- a/remotefilelog/__init__.py
+++ b/remotefilelog/__init__.py
@@ -18,6 +18,8 @@
     ``remotefilelog.nodettl`` specifies maximum TTL of a node in seconds before
       it is garbage collected
     ``remotefilelog.repackonhggc`` runs repack on hg gc when True
+    ``remotefilelog.prefetchdays`` specifies the maximum age of a commit in
+      days after which it is no longer prefetched.
 """
 
 from . import fileserverclient, remotefilelog, remotefilectx, shallowstore
@@ -789,6 +791,11 @@
     if shallow and bgprefetchrevs:
         bgrepack = repo.ui.configbool('remotefilelog',
                                       'backgroundrepack', False)
+        # only prefetch changesets no older than 'prefetchdays' days
+        # default value is set to 14 days
+        days = ui.configint('remotefilelog', 'prefetchdays', 14)
+        bgprefetchrevs = '(%s) & date(-%s)' % (bgprefetchrevs, days)
+
         def anon():
             if util.safehasattr(repo, 'ranprefetch') and repo.ranprefetch:
                 return
@@ -929,8 +936,12 @@
         bgprefetchrevs = ui.config('remotefilelog', 'bgprefetchrevs', None)
         if bgprefetchrevs:
             revset.append('(%s)' % bgprefetchrevs)
+        revset = '+'.join(revset)
 
-        opts['rev'] = ['+'.join(revset)]
+        # only prefetch changesets no older than 'prefetchdays' days
+        # default value is set to 14 days
+        days = ui.configint('remotefilelog', 'prefetchdays', 14)
+        opts['rev'] = ['(%s) & date(-%s)' % (revset, days)]
 
     revs = scmutil.revrange(repo, opts.get('rev'))
 
diff --git a/tests/test-remotefilelog-bgprefetch.t b/tests/test-remotefilelog-bgprefetch.t
--- a/tests/test-remotefilelog-bgprefetch.t
+++ b/tests/test-remotefilelog-bgprefetch.t
@@ -22,7 +22,7 @@
 
   $ cd ..
 
-# prefetch a revision
+# clone the repo
 
   $ hgcloneshallow ssh://user@dummy/master shallow --noupdate
   streaming all changes
@@ -30,6 +30,17 @@
   transferred 776 bytes in * seconds (*/sec) (glob)
   searching for changes
   no changes found
+
+# For the purposes of the test prefetchdays is set to current days since epoch + 100 days. i.e. all commits in tests have
+# a date of 1970 and therefore to prefetch all revisions we have to set prefetchdays to be farther from 1970 than we are now.
+  $ cd shallow
+  $ cat >> .hg/hgrc <<EOF
+  > [remotefilelog]
+  > prefetchdays=$(($(date +%s) + 100))
+  > EOF
+  $ cd ..
+
+# prefetch a revision
   $ cd shallow
 
   $ hg prefetch -r 0
diff --git a/tests/test-remotefilelog-gc.t b/tests/test-remotefilelog-gc.t
--- a/tests/test-remotefilelog-gc.t
+++ b/tests/test-remotefilelog-gc.t
@@ -17,6 +17,15 @@
   $ hgcloneshallow ssh://user@dummy/master shallow -q
   1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
 
+# For the purposes of the test prefetchdays is set to current days since epoch + 100 days. i.e. all commits in tests have
+# a date of 1970 and therefore to prefetch all revisions we have to set prefetchdays to be farther from 1970 than we are now.
+  $ cd shallow
+  $ cat >> .hg/hgrc <<EOF
+  > [remotefilelog]
+  > prefetchdays=$(($(date +%s) + 100))
+  > EOF
+  $ cd ..
+
 # commit a new version of x so we can gc the old one
 
   $ cd master
diff --git a/tests/test-remotefilelog-gcrepack.t b/tests/test-remotefilelog-gcrepack.t
--- a/tests/test-remotefilelog-gcrepack.t
+++ b/tests/test-remotefilelog-gcrepack.t
@@ -21,6 +21,15 @@
   $ hgcloneshallow ssh://user@dummy/master shallow -q
   1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
 
+# For the purposes of the test prefetchdays is set to current days since epoch + 100 days. i.e. all commits in tests have
+# a date of 1970 and therefore to prefetch all revisions we have to set prefetchdays to be farther from 1970 than we are now.
+  $ cd shallow
+  $ cat >> .hg/hgrc <<EOF
+  > [remotefilelog]
+  > prefetchdays=$(($(date +%s) + 100))
+  > EOF
+  $ cd ..
+
 # Prefetch all data and repack
 
   $ cd shallow
diff --git a/tests/test-remotefilelog-repack-fast.t b/tests/test-remotefilelog-repack-fast.t
--- a/tests/test-remotefilelog-repack-fast.t
+++ b/tests/test-remotefilelog-repack-fast.t
@@ -24,6 +24,15 @@
   $ hgcloneshallow ssh://user@dummy/master shallow -q
   1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
 
+# For the purposes of the test prefetchdays is set to current days since epoch + 100 days. i.e. all commits in tests have
+# a date of 1970 and therefore to prefetch all revisions we have to set prefetchdays to be farther from 1970 than we are now.
+  $ cd shallow
+  $ cat >> .hg/hgrc <<EOF
+  > [remotefilelog]
+  > prefetchdays=$(($(date +%s) + 100))
+  > EOF
+  $ cd ..
+
 # Test that repack cleans up the old files and creates new packs
 
   $ cd shallow
diff --git a/tests/test-remotefilelog-repack.t b/tests/test-remotefilelog-repack.t
--- a/tests/test-remotefilelog-repack.t
+++ b/tests/test-remotefilelog-repack.t
@@ -19,6 +19,15 @@
   $ hgcloneshallow ssh://user@dummy/master shallow -q
   1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
 
+# For the purposes of the test prefetchdays is set to current days since epoch + 100 days. i.e. all commits in tests have
+# a date of 1970 and therefore to prefetch all revisions we have to set prefetchdays to be farther from 1970 than we are now.
+  $ cd shallow
+  $ cat >> .hg/hgrc <<EOF
+  > [remotefilelog]
+  > prefetchdays=$(($(date +%s) + 100))
+  > EOF
+  $ cd ..
+
 # Test that repack cleans up the old files and creates new packs
 
   $ cd shallow