diff --git a/hgext/lfs/__init__.py b/hgext/lfs/__init__.py
--- a/hgext/lfs/__init__.py
+++ b/hgext/lfs/__init__.py
@@ -19,8 +19,23 @@ Configs::
     # (default: unset)
     url = https://example.com/lfs
 
-    # size of a file to make it use LFS
-    threshold = 10M
+    # Which files to track in LFS.  Path tests are "**.extname" for file
+    # extensions, and "path:under/some/directory" for path prefix.  Both
+    # are relative to the repository root, and the latter must be quoted.
+    # File size can be tested with the "size()" fileset, and tests can be
+    # joined with fileset operators.  (See "hg help filesets.operators".)
+    #
+    # Some examples:
+    # - all()                       # everything
+    # - none()                      # nothing
+    # - size(">20MB")               # larger than 20MB
+    # - !**.txt                     # anything not a *.txt file
+    # - **.zip | **.tar.gz | **.7z  # some types of compressed files
+    # - "path:bin"                  # files under "bin" in the project root
+    # - (**.php & size(">2MB")) | (**.js & size(">5MB")) | **.tar.gz
+    #     | ("path:bin" & !"path:/bin/README") | size(">1GB")
+    # (default: none())
+    track = size(">10M")
 
     # how many times to retry before giving up on transferring an object
     retry = 5
@@ -41,8 +56,10 @@ from mercurial import (
     exchange,
     extensions,
     filelog,
+    fileset,
     hg,
     localrepo,
+    minifileset,
     node,
     registrar,
     revlog,
@@ -76,9 +93,13 @@ configitem('lfs', 'url',
 configitem('lfs', 'usercache',
     default=None,
 )
+# Deprecated
 configitem('lfs', 'threshold',
     default=None,
 )
+configitem('lfs', 'track',
+    default='none()',
+)
 configitem('lfs', 'retry',
     default=5,
 )
@@ -100,9 +121,15 @@ def reposetup(ui, repo):
     if not repo.local():
         return
 
-    threshold = repo.ui.configbytes('lfs', 'threshold')
+    trackspec = repo.ui.config('lfs', 'track')
 
-    repo.svfs.options['lfsthreshold'] = threshold
+    # deprecated config: lfs.threshold
+    threshold = repo.ui.configbytes('lfs', 'threshold')
+    if threshold:
+        fileset.parse(trackspec)  # make sure syntax errors are confined
+        trackspec = "(%s) | size('>%d')" % (trackspec, threshold)
+
+    repo.svfs.options['lfstrack'] = minifileset.compile(trackspec)
     repo.svfs.lfslocalblobstore = blobstore.local(repo)
     repo.svfs.lfsremoteblobstore = blobstore.remote(repo)
 
diff --git a/hgext/lfs/wrapper.py b/hgext/lfs/wrapper.py
--- a/hgext/lfs/wrapper.py
+++ b/hgext/lfs/wrapper.py
@@ -123,14 +123,14 @@ def _islfs(rlog, node=None, rev=None):
 def filelogaddrevision(orig, self, text, transaction, link, p1, p2,
                        cachedelta=None, node=None,
                        flags=revlog.REVIDX_DEFAULT_FLAGS, **kwds):
-    threshold = self.opener.options['lfsthreshold']
     textlen = len(text)
     # exclude hg rename meta from file size
     meta, offset = filelog.parsemeta(text)
     if offset:
         textlen -= offset
 
-    if threshold and textlen > threshold:
+    lfstrack = self.opener.options['lfstrack']
+    if lfstrack(self.filename, textlen):
         flags |= revlog.REVIDX_EXTSTORED
 
     return orig(self, text, transaction, link, p1, p2, cachedelta=cachedelta,
diff --git a/tests/test-lfs-test-server.t b/tests/test-lfs-test-server.t
--- a/tests/test-lfs-test-server.t
+++ b/tests/test-lfs-test-server.t
@@ -30,7 +30,7 @@
   > lfs=
   > [lfs]
   > url=http://foo:bar@$LFS_HOST/
-  > threshold=1
+  > track=all()
   > EOF
 
   $ hg init repo1
diff --git a/tests/test-lfs.t b/tests/test-lfs.t
--- a/tests/test-lfs.t
+++ b/tests/test-lfs.t
@@ -4,6 +4,7 @@
   > [extensions]
   > lfs=
   > [lfs]
+  > # Test deprecated config
   > threshold=1000B
   > EOF
 
@@ -140,7 +141,7 @@ enabled adds the lfs requirement
   $ cd repo3
   $ cat >> .hg/hgrc << EOF
   > [lfs]
-  > threshold=10B
+  > track=size(">10B")
   > EOF
 
   $ echo LONGER-THAN-TEN-BYTES-WILL-TRIGGER-LFS > large
@@ -203,7 +204,7 @@ enabled adds the lfs requirement
   $ cd repo6
   $ cat >> .hg/hgrc << EOF
   > [lfs]
-  > threshold=30B
+  > track=size(">30B")
   > EOF
 
   $ echo LARGE-BECAUSE-IT-IS-MORE-THAN-30-BYTES > large
@@ -239,7 +240,7 @@ enabled adds the lfs requirement
   $ cd repo8
   $ cat >> .hg/hgrc << EOF
   > [lfs]
-  > threshold=10B
+  > track=size(">10B")
   > EOF
 
   $ echo THIS-IS-LFS-BECAUSE-10-BYTES > a1
@@ -320,7 +321,7 @@ enabled adds the lfs requirement
   $ cd repo9
   $ cat >> .hg/hgrc << EOF
   > [lfs]
-  > threshold=10B
+  > track=size(">10B")
   > [diff]
   > git=1
   > EOF
@@ -454,7 +455,7 @@ enabled adds the lfs requirement
   > [extensions]
   > lfs=
   > [lfs]
-  > threshold=1
+  > track=all()
   > EOF
   $ $PYTHON <<'EOF'
   > def write(path, content):
@@ -542,6 +543,47 @@ enabled adds the lfs requirement
 
   $ cd ..
 
+# Test filter
+
+  $ hg init repo11
+  $ cd repo11
+  $ cat >> .hg/hgrc << EOF
+  > [lfs]
+  > track=(**.a & size(">5B")) | (**.b & !size(">5B"))
+  >      | (**.c & "path:d" & !"path:d/c.c") | size(">10B")
+  > EOF
+
+  $ mkdir a
+  $ echo aaaaaa > a/1.a
+  $ echo a > a/2.a
+  $ echo aaaaaa > 1.b
+  $ echo a > 2.b
+  $ echo a > 1.c
+  $ mkdir d
+  $ echo a > d/c.c
+  $ echo a > d/d.c
+  $ echo aaaaaaaaaaaa > x
+  $ hg add . -q
+  $ hg commit -m files
+
+  $ for p in a/1.a a/2.a 1.b 2.b 1.c d/c.c d/d.c x; do
+  >   if hg debugdata $p 0 2>&1 | grep git-lfs >/dev/null; then
+  >     echo "${p}: is lfs"
+  >   else
+  >     echo "${p}: not lfs"
+  >   fi
+  > done
+  a/1.a: is lfs
+  a/2.a: not lfs
+  1.b: not lfs
+  2.b: is lfs
+  1.c: not lfs
+  d/c.c: not lfs
+  d/d.c: is lfs
+  x: is lfs
+
+  $ cd ..
+
 # Verify the repos
 
   $ cat > $TESTTMP/dumpflog.py << EOF