--- a/vcssync/mozvcssync/cli.py
+++ b/vcssync/mozvcssync/cli.py
@@ -188,17 +188,18 @@ def linearize_git_to_hg():
             args.hg_repo_path,
             git_push_url=args.git_push_url,
             hg_push_url=args.hg_push_url,
             move_to_subdir=args.move_to_subdir,
             find_copies_harder=args.find_copies_harder,
             skip_submodules=args.skip_submodules,
             similarity=args.similarity,
             shamap_s3_upload_url=args.shamap_s3_upload_url,
-            git_commit_rewriter_args=rewriter_args)
+            git_commit_rewriter_args=rewriter_args,
+            exclude_dirs=args.exclude_dirs)
     except RewriteError as e:
         logger.error('abort: %s' % str(e))
         sys.exit(1)
     except subprocess.CalledProcessError:
         sys.exit(1)
 
 
 def overlay_hg_repos_cli():

--- a/vcssync/mozvcssync/git2hg.py
+++ b/vcssync/mozvcssync/git2hg.py
@@ -27,17 +27,18 @@ logger = logging.getLogger(__name__)
 def linearize_git_repo_to_hg(git_source_url, ref, git_repo_path, hg_repo_path,
                              git_push_url=None,
                              hg_push_url=None,
                              move_to_subdir=None,
                              find_copies_harder=False,
                              skip_submodules=False,
                              similarity=50,
                              shamap_s3_upload_url=None,
-                             git_commit_rewriter_args=None):
+                             git_commit_rewriter_args=None,
+                             exclude_dirs=None):
     """Linearize a Git repo to an hg repo by squashing merges.
 
     Many Git repositories (especially those on GitHub) have an excessive
     number of merge commits and don't practice "every commit is
     good/bisectable." When converting these repositories to Mercurial, it is
     often desirable to ignore the non-first-parent ancestry so the result has
     more readable history.
 
@@ -108,17 +109,18 @@ def linearize_git_repo_to_hg(git_source_
 
     rewriter = commit_metadata_rewriter(git_repo,
                                         source_repo=git_source_url,
                                         **git_commit_rewriter_args)
 
     git_state = linearize_git_repo(
         git_repo,
         b'heads/%s' % ref,
-        commit_rewriter=rewriter)
+        commit_rewriter=rewriter,
+        exclude_dirs=exclude_dirs)
 
     if git_push_url:
         subprocess.check_call([b'git', b'push', b'--mirror', git_push_url],
                               cwd=git_repo_path)
 
     rev_map = os.path.join(hg_repo_path, b'.hg', b'shamap')
 
     def maybe_push_hg():

new file mode 100644
--- /dev/null
+++ b/vcssync/tests/test-linearize-git-to-hg-exclude-dirs.t
@@ -0,0 +1,115 @@
+#require hg41+
+
+  $ . $TESTDIR/vcssync/tests/helpers.sh
+
+  $ standardgitrepo grepo > /dev/null 2>&1
+  $ linearize-git-to-hg file://$TESTTMP/grepo master grepo-source grepo-dest > /dev/null 2>&1
+
+Directories can be excluded when linearizing
+
+  $ cd grepo
+  $ mkdir dir1
+  $ echo 0 > dir1/dir1_file0
+  $ echo 1 > dir1/dir1_file1
+  $ git add --all
+  $ git commit -m ignore > /dev/null
+  $ cd ..
+
+  $ linearize-git-to-hg file://$TESTTMP/grepo master grepo-source grepo-dest --exclude-dir dir1
+  From file://$TESTTMP/grepo
+     a447b9b..ad3f6b5  master     -> master
+  linearizing 1 commits from heads/master (ad3f6b56f7320d386c2ce2574b0573d1ad88773b to ad3f6b56f7320d386c2ce2574b0573d1ad88773b)
+  1/1 ad3f6b56f7320d386c2ce2574b0573d1ad88773b ignore
+  dropping ad3f6b56f7320d386c2ce2574b0573d1ad88773b because no tree changes
+  0 commits from heads/master converted; original: ad3f6b56f7320d386c2ce2574b0573d1ad88773b; rewritten: aea30981234cf6848489e0ccf541fbf902b27aca
+  all Git commits have already been converted; not doing anything
+  $ cd grepo-dest
+  $ hg co tip > /dev/null
+  $ ls
+  bar
+  file0-copied-with-move
+  file0-copy0
+  file0-copy1
+  file0-copy2
+  file0-moved-with-copy
+  file1
+  file1-20
+  file1-50
+  file1-80
+  foo
+  $ cd ..
+
+--exclude-dir works multiple times
+
+  $ cd grepo
+  $ mkdir dir2
+  $ echo 0 > dir2/file0
+  $ git add --all
+  $ git commit -m ignore-multi > /dev/null
+  $ cd ..
+
+  $ linearize-git-to-hg file://$TESTTMP/grepo master grepo-source grepo-dest --exclude-dir dir1 --exclude-dir dir2
+  From file://$TESTTMP/grepo
+     ad3f6b5..04ac57d  master     -> master
+  linearizing 1 commits from heads/master (04ac57d95ed6dd954cceead6f95fcbb047c80760 to 04ac57d95ed6dd954cceead6f95fcbb047c80760)
+  1/1 04ac57d95ed6dd954cceead6f95fcbb047c80760 ignore-multi
+  dropping 04ac57d95ed6dd954cceead6f95fcbb047c80760 because no tree changes
+  0 commits from heads/master converted; original: 04ac57d95ed6dd954cceead6f95fcbb047c80760; rewritten: aea30981234cf6848489e0ccf541fbf902b27aca
+  all Git commits have already been converted; not doing anything
+  $ cd grepo-dest
+  $ hg co tip > /dev/null
+  $ ls
+  bar
+  file0-copied-with-move
+  file0-copy0
+  file0-copy1
+  file0-copy2
+  file0-moved-with-copy
+  file1
+  file1-20
+  file1-50
+  file1-80
+  foo
+  $ cd ..
+
+Excluding an intermediate directory works  --exclude-dir ignore2/subdir0
+
+  $ cd grepo
+  $ mkdir -p dir3/subdir0
+  $ echo 0 > dir3/file0
+  $ echo 1 > dir3/subdir0/file1
+  $ git add --all
+  $ git commit -m ignore-multi > /dev/null
+  $ cd ..
+
+  $ linearize-git-to-hg file://$TESTTMP/grepo master grepo-source grepo-dest --exclude-dir dir1 --exclude-dir dir2 --exclude-dir dir3/subdir0
+  From file://$TESTTMP/grepo
+     04ac57d..36d2de4  master     -> master
+  linearizing 1 commits from heads/master (36d2de48325568c9bce9ff67d66ed6aca4c9b2e9 to 36d2de48325568c9bce9ff67d66ed6aca4c9b2e9)
+  1/1 36d2de48325568c9bce9ff67d66ed6aca4c9b2e9 ignore-multi
+  1 commits from heads/master converted; original: 36d2de48325568c9bce9ff67d66ed6aca4c9b2e9; rewritten: 95c25188f219f5c68497863faba183fbbbbfae04
+  converting 1 Git commits
+  scanning source...
+  sorting...
+  converting...
+  0 ignore-multi
+  1 Git commits converted to Mercurial; previous tip: 10:7d80acaa161029d9e746e3125e7cc0916406403f; current tip: 11:4c82e4e6f1944acf408939cee63fc5c078de73df
+  $ cd grepo-dest
+  $ hg co tip > /dev/null
+  $ ls -R
+  bar
+  dir3
+  file0-copied-with-move
+  file0-copy0
+  file0-copy1
+  file0-copy2
+  file0-moved-with-copy
+  file1
+  file1-20
+  file1-50
+  file1-80
+  foo
+  
+  ./dir3:
+  file0
+  $ cd ..