diff --git a/pre_commit/clientlib.py b/pre_commit/clientlib.py
index e69359b0..7fb49d78 100644
--- a/pre_commit/clientlib.py
+++ b/pre_commit/clientlib.py
@@ -130,6 +130,7 @@ CONFIG_SCHEMA = schema.Map(
     'Config', None,
 
     schema.RequiredRecurse('repos', schema.Array(CONFIG_REPO_DICT)),
+    schema.Optional('fail_fast', schema.check_bool, False),
 )
 
 
diff --git a/pre_commit/commands/autoupdate.py b/pre_commit/commands/autoupdate.py
index 17588cc3..4dce674f 100644
--- a/pre_commit/commands/autoupdate.py
+++ b/pre_commit/commands/autoupdate.py
@@ -9,10 +9,12 @@ from aspy.yaml import ordered_load
 
 import pre_commit.constants as C
 from pre_commit import output
+from pre_commit.clientlib import CONFIG_SCHEMA
 from pre_commit.clientlib import is_local_repo
 from pre_commit.clientlib import load_config
 from pre_commit.commands.migrate_config import migrate_config
 from pre_commit.repository import Repository
+from pre_commit.schema import remove_defaults
 from pre_commit.util import CalledProcessError
 from pre_commit.util import cmd_output
 from pre_commit.util import cwd
@@ -71,6 +73,7 @@ SHA_LINE_FMT = '{}sha:{}{}{}'
 
 def _write_new_config_file(path, output):
     original_contents = open(path).read()
+    output = remove_defaults(output, CONFIG_SCHEMA)
     new_contents = ordered_dump(output, **C.YAML_DUMP_KWARGS)
 
     lines = original_contents.splitlines(True)
@@ -95,7 +98,7 @@ def _write_new_config_file(path, output):
     # If we failed to intelligently rewrite the sha lines, fall back to the
     # pretty-formatted yaml output
     to_write = ''.join(lines)
-    if ordered_load(to_write) != output:
+    if remove_defaults(ordered_load(to_write), CONFIG_SCHEMA) != output:
         to_write = new_contents
 
     with open(path, 'w') as f:
diff --git a/pre_commit/commands/run.py b/pre_commit/commands/run.py
index 99232585..505bb54d 100644
--- a/pre_commit/commands/run.py
+++ b/pre_commit/commands/run.py
@@ -169,13 +169,15 @@ def _compute_cols(hooks, verbose):
     return max(cols, 80)
 
 
-def _run_hooks(repo_hooks, args, environ):
+def _run_hooks(config, repo_hooks, args, environ):
     """Actually run the hooks."""
     skips = _get_skips(environ)
     cols = _compute_cols([hook for _, hook in repo_hooks], args.verbose)
     retval = 0
     for repo, hook in repo_hooks:
         retval |= _run_single_hook(hook, repo, args, skips, cols)
+        if retval and config['fail_fast']:
+            break
     if (
             retval and
             args.show_diff_on_failure and
@@ -251,4 +253,4 @@ def run(runner, args, environ=os.environ):
             if not hook['stages'] or args.hook_stage in hook['stages']
         ]
 
-        return _run_hooks(repo_hooks, args, environ)
+        return _run_hooks(runner.config, repo_hooks, args, environ)
diff --git a/pre_commit/runner.py b/pre_commit/runner.py
index 346d6021..d853868a 100644
--- a/pre_commit/runner.py
+++ b/pre_commit/runner.py
@@ -37,10 +37,14 @@ class Runner(object):
     def config_file_path(self):
         return os.path.join(self.git_root, self.config_file)
 
+    @cached_property
+    def config(self):
+        return load_config(self.config_file_path)
+
     @cached_property
     def repositories(self):
         """Returns a tuple of the configured repositories."""
-        repos = load_config(self.config_file_path)['repos']
+        repos = self.config['repos']
         repos = tuple(Repository.create(x, self.store) for x in repos)
         for repo in repos:
             repo.require_installed()
diff --git a/pre_commit/schema.py b/pre_commit/schema.py
index f033071f..e20f74cc 100644
--- a/pre_commit/schema.py
+++ b/pre_commit/schema.py
@@ -64,6 +64,11 @@ def _apply_default_optional(self, dct):
     dct.setdefault(self.key, self.default)
 
 
+def _remove_default_optional(self, dct):
+    if dct.get(self.key, MISSING) == self.default:
+        del dct[self.key]
+
+
 def _require_key(self, dct):
     if self.key not in dct:
         raise ValidationError('Missing required key: {}'.format(self.key))
@@ -85,6 +90,10 @@ def _apply_default_required_recurse(self, dct):
     dct[self.key] = apply_defaults(dct[self.key], self.schema)
 
 
+def _remove_default_required_recurse(self, dct):
+    dct[self.key] = remove_defaults(dct[self.key], self.schema)
+
+
 def _check_conditional(self, dct):
     if dct.get(self.condition_key, MISSING) == self.condition_value:
         _check_required(self, dct)
@@ -110,18 +119,22 @@ def _check_conditional(self, dct):
 Required = collections.namedtuple('Required', ('key', 'check_fn'))
 Required.check = _check_required
 Required.apply_default = _dct_noop
+Required.remove_default = _dct_noop
 RequiredRecurse = collections.namedtuple('RequiredRecurse', ('key', 'schema'))
 RequiredRecurse.check = _check_required
 RequiredRecurse.check_fn = _check_fn_required_recurse
 RequiredRecurse.apply_default = _apply_default_required_recurse
+RequiredRecurse.remove_default = _remove_default_required_recurse
 Optional = collections.namedtuple('Optional', ('key', 'check_fn', 'default'))
 Optional.check = _check_optional
 Optional.apply_default = _apply_default_optional
+Optional.remove_default = _remove_default_optional
 OptionalNoDefault = collections.namedtuple(
     'OptionalNoDefault', ('key', 'check_fn'),
 )
 OptionalNoDefault.check = _check_optional
 OptionalNoDefault.apply_default = _dct_noop
+OptionalNoDefault.remove_default = _dct_noop
 Conditional = collections.namedtuple(
     'Conditional',
     ('key', 'check_fn', 'condition_key', 'condition_value', 'ensure_absent'),
@@ -129,6 +142,7 @@ Conditional = collections.namedtuple(
 Conditional.__new__.__defaults__ = (False,)
 Conditional.check = _check_conditional
 Conditional.apply_default = _dct_noop
+Conditional.remove_default = _dct_noop
 
 
 class Map(collections.namedtuple('Map', ('object_name', 'id_key', 'items'))):
@@ -158,6 +172,12 @@ class Map(collections.namedtuple('Map', ('object_name', 'id_key', 'items'))):
             item.apply_default(ret)
         return ret
 
+    def remove_defaults(self, v):
+        ret = v.copy()
+        for item in self.items:
+            item.remove_default(ret)
+        return ret
+
 
 class Array(collections.namedtuple('Array', ('of',))):
     __slots__ = ()
@@ -174,6 +194,9 @@ class Array(collections.namedtuple('Array', ('of',))):
     def apply_defaults(self, v):
         return [apply_defaults(val, self.of) for val in v]
 
+    def remove_defaults(self, v):
+        return [remove_defaults(val, self.of) for val in v]
+
 
 class Not(object):
     def __init__(self, val):
@@ -238,6 +261,10 @@ def apply_defaults(v, schema):
     return schema.apply_defaults(v)
 
 
+def remove_defaults(v, schema):
+    return schema.remove_defaults(v)
+
+
 def load_from_filename(filename, schema, load_strategy, exc_tp):
     with reraise_as(exc_tp):
         if not os.path.exists(filename):
diff --git a/tests/commands/autoupdate_test.py b/tests/commands/autoupdate_test.py
index 7fb21b9d..2877c5b3 100644
--- a/tests/commands/autoupdate_test.py
+++ b/tests/commands/autoupdate_test.py
@@ -275,7 +275,7 @@ def test_autoupdate_local_hooks(tempdir_factory):
     runner = Runner(path, C.CONFIG_FILE)
     assert autoupdate(runner, tags_only=False) == 0
     new_config_writen = load_config(runner.config_file_path)
-    assert len(new_config_writen) == 1
+    assert len(new_config_writen['repos']) == 1
     assert new_config_writen['repos'][0] == config
 
 
diff --git a/tests/commands/run_test.py b/tests/commands/run_test.py
index 39d3ac0b..53e098b0 100644
--- a/tests/commands/run_test.py
+++ b/tests/commands/run_test.py
@@ -729,3 +729,18 @@ def test_pass_filenames(
     )
     assert expected_out + b'\nHello World' in printed
     assert (b'foo.py' in printed) == pass_filenames
+
+
+def test_fail_fast(
+        cap_out, repo_with_failing_hook, mock_out_store_directory,
+):
+    with cwd(repo_with_failing_hook):
+        with modify_config() as config:
+            # More than one hook
+            config['fail_fast'] = True
+            config['repos'][0]['hooks'] *= 2
+        stage_a_file()
+
+        ret, printed = _do_run(cap_out, repo_with_failing_hook, _get_opts())
+        # it should have only run one hook
+        assert printed.count(b'Failing hook') == 1
diff --git a/tests/schema_test.py b/tests/schema_test.py
index c133a997..c2ecf0fa 100644
--- a/tests/schema_test.py
+++ b/tests/schema_test.py
@@ -21,6 +21,7 @@ from pre_commit.schema import MISSING
 from pre_commit.schema import Not
 from pre_commit.schema import Optional
 from pre_commit.schema import OptionalNoDefault
+from pre_commit.schema import remove_defaults
 from pre_commit.schema import Required
 from pre_commit.schema import RequiredRecurse
 from pre_commit.schema import validate
@@ -280,6 +281,37 @@ def test_apply_defaults_map_in_list():
     assert ret == [{'key': False}]
 
 
+def test_remove_defaults_copies_object():
+    val = {'key': False}
+    ret = remove_defaults(val, map_optional)
+    assert ret is not val
+
+
+def test_remove_defaults_removes_defaults():
+    ret = remove_defaults({'key': False}, map_optional)
+    assert ret == {}
+
+
+def test_remove_defaults_nothing_to_remove():
+    ret = remove_defaults({}, map_optional)
+    assert ret == {}
+
+
+def test_remove_defaults_does_not_change_non_default():
+    ret = remove_defaults({'key': True}, map_optional)
+    assert ret == {'key': True}
+
+
+def test_remove_defaults_map_in_list():
+    ret = remove_defaults([{'key': False}], Array(map_optional))
+    assert ret == [{}]
+
+
+def test_remove_defaults_does_nothing_on_non_optional():
+    ret = remove_defaults({'key': True}, map_required)
+    assert ret == {'key': True}
+
+
 nested_schema_required = Map(
     'Repository', 'repo',
     Required('repo', check_any),
@@ -310,6 +342,12 @@ def test_apply_defaults_nested():
     assert ret == {'repo': 'repo1', 'hooks': [{'key': False}]}
 
 
+def test_remove_defaults_nested():
+    val = {'repo': 'repo1', 'hooks': [{'key': False}]}
+    ret = remove_defaults(val, nested_schema_optional)
+    assert ret == {'repo': 'repo1', 'hooks': [{}]}
+
+
 class Error(Exception):
     pass