diff --git a/pre_commit/commands/run.py b/pre_commit/commands/run.py
index 97d56b8d..651c7f3f 100644
--- a/pre_commit/commands/run.py
+++ b/pre_commit/commands/run.py
@@ -17,14 +17,47 @@ from pre_commit.repository import all_hooks
 from pre_commit.repository import install_hook_envs
 from pre_commit.staged_files_only import staged_files_only
 from pre_commit.util import cmd_output
-from pre_commit.util import memoize_by_cwd
 from pre_commit.util import noop_context
 
 
 logger = logging.getLogger('pre_commit')
 
 
-tags_from_path = memoize_by_cwd(tags_from_path)
+def filter_by_include_exclude(names, include, exclude):
+    include_re, exclude_re = re.compile(include), re.compile(exclude)
+    return [
+        filename for filename in names
+        if include_re.search(filename)
+        if not exclude_re.search(filename)
+    ]
+
+
+class Classifier(object):
+    def __init__(self, filenames):
+        self.filenames = [f for f in filenames if os.path.lexists(f)]
+        self._types_cache = {}
+
+    def _types_for_file(self, filename):
+        try:
+            return self._types_cache[filename]
+        except KeyError:
+            ret = self._types_cache[filename] = tags_from_path(filename)
+            return ret
+
+    def by_types(self, names, types, exclude_types):
+        types, exclude_types = frozenset(types), frozenset(exclude_types)
+        ret = []
+        for filename in names:
+            tags = self._types_for_file(filename)
+            if tags >= types and not tags & exclude_types:
+                ret.append(filename)
+        return ret
+
+    def filenames_for_hook(self, hook):
+        names = self.filenames
+        names = filter_by_include_exclude(names, hook.files, hook.exclude)
+        names = self.by_types(names, hook.types, hook.exclude_types)
+        return names
 
 
 def _get_skips(environ):
@@ -36,37 +69,12 @@ def _hook_msg_start(hook, verbose):
     return '{}{}'.format('[{}] '.format(hook.id) if verbose else '', hook.name)
 
 
-def _filter_by_include_exclude(filenames, include, exclude):
-    include_re, exclude_re = re.compile(include), re.compile(exclude)
-    return [
-        filename for filename in filenames
-        if (
-            include_re.search(filename) and
-            not exclude_re.search(filename) and
-            os.path.lexists(filename)
-        )
-    ]
-
-
-def _filter_by_types(filenames, types, exclude_types):
-    types, exclude_types = frozenset(types), frozenset(exclude_types)
-    ret = []
-    for filename in filenames:
-        tags = tags_from_path(filename)
-        if tags >= types and not tags & exclude_types:
-            ret.append(filename)
-    return tuple(ret)
-
-
 SKIPPED = 'Skipped'
 NO_FILES = '(no files to check)'
 
 
-def _run_single_hook(filenames, hook, args, skips, cols):
-    include, exclude = hook.files, hook.exclude
-    filenames = _filter_by_include_exclude(filenames, include, exclude)
-    types, exclude_types = hook.types, hook.exclude_types
-    filenames = _filter_by_types(filenames, types, exclude_types)
+def _run_single_hook(classifier, hook, args, skips, cols):
+    filenames = classifier.filenames_for_hook(hook)
 
     if hook.language == 'pcre':
         logger.warning(
@@ -193,10 +201,11 @@ def _run_hooks(config, hooks, args, environ):
     skips = _get_skips(environ)
     cols = _compute_cols(hooks, args.verbose)
     filenames = _all_filenames(args)
-    filenames = _filter_by_include_exclude(filenames, '', config['exclude'])
+    filenames = filter_by_include_exclude(filenames, '', config['exclude'])
+    classifier = Classifier(filenames)
     retval = 0
     for hook in hooks:
-        retval |= _run_single_hook(filenames, hook, args, skips, cols)
+        retval |= _run_single_hook(classifier, hook, args, skips, cols)
         if retval and config['fail_fast']:
             break
     if retval and args.show_diff_on_failure and git.has_diff():
diff --git a/pre_commit/meta_hooks/check_hooks_apply.py b/pre_commit/meta_hooks/check_hooks_apply.py
index b17a9d6f..b1ccdac3 100644
--- a/pre_commit/meta_hooks/check_hooks_apply.py
+++ b/pre_commit/meta_hooks/check_hooks_apply.py
@@ -3,24 +3,19 @@ import argparse
 import pre_commit.constants as C
 from pre_commit import git
 from pre_commit.clientlib import load_config
-from pre_commit.commands.run import _filter_by_include_exclude
-from pre_commit.commands.run import _filter_by_types
+from pre_commit.commands.run import Classifier
 from pre_commit.repository import all_hooks
 from pre_commit.store import Store
 
 
 def check_all_hooks_match_files(config_file):
-    files = git.get_all_files()
+    classifier = Classifier(git.get_all_files())
     retv = 0
 
     for hook in all_hooks(load_config(config_file), Store()):
         if hook.always_run or hook.language == 'fail':
             continue
-        include, exclude = hook.files, hook.exclude
-        filtered = _filter_by_include_exclude(files, include, exclude)
-        types, exclude_types = hook.types, hook.exclude_types
-        filtered = _filter_by_types(filtered, types, exclude_types)
-        if not filtered:
+        elif not classifier.filenames_for_hook(hook):
             print('{} does not apply to this repository'.format(hook.id))
             retv = 1
 
diff --git a/pre_commit/meta_hooks/check_useless_excludes.py b/pre_commit/meta_hooks/check_useless_excludes.py
index 18b9f163..c4860db3 100644
--- a/pre_commit/meta_hooks/check_useless_excludes.py
+++ b/pre_commit/meta_hooks/check_useless_excludes.py
@@ -9,7 +9,7 @@ import pre_commit.constants as C
 from pre_commit import git
 from pre_commit.clientlib import load_config
 from pre_commit.clientlib import MANIFEST_HOOK_DICT
-from pre_commit.commands.run import _filter_by_types
+from pre_commit.commands.run import Classifier
 
 
 def exclude_matches_any(filenames, include, exclude):
@@ -24,11 +24,11 @@ def exclude_matches_any(filenames, include, exclude):
 
 def check_useless_excludes(config_file):
     config = load_config(config_file)
-    files = git.get_all_files()
+    classifier = Classifier(git.get_all_files())
     retv = 0
 
     exclude = config['exclude']
-    if not exclude_matches_any(files, '', exclude):
+    if not exclude_matches_any(classifier.filenames, '', exclude):
         print(
             'The global exclude pattern {!r} does not match any files'
             .format(exclude),
@@ -40,10 +40,11 @@ def check_useless_excludes(config_file):
             # Not actually a manifest dict, but this more accurately reflects
             # the defaults applied during runtime
             hook = apply_defaults(hook, MANIFEST_HOOK_DICT)
+            names = classifier.filenames
             types, exclude_types = hook['types'], hook['exclude_types']
-            filtered_by_types = _filter_by_types(files, types, exclude_types)
+            names = classifier.by_types(names, types, exclude_types)
             include, exclude = hook['files'], hook['exclude']
-            if not exclude_matches_any(filtered_by_types, include, exclude):
+            if not exclude_matches_any(names, include, exclude):
                 print(
                     'The exclude pattern {!r} for {} does not match any files'
                     .format(exclude, hook['id']),
diff --git a/pre_commit/util.py b/pre_commit/util.py
index c38af5a2..4c390289 100644
--- a/pre_commit/util.py
+++ b/pre_commit/util.py
@@ -2,7 +2,6 @@ from __future__ import unicode_literals
 
 import contextlib
 import errno
-import functools
 import os.path
 import shutil
 import stat
@@ -31,23 +30,6 @@ def mkdirp(path):
             raise
 
 
-def memoize_by_cwd(func):
-    """Memoize a function call based on os.getcwd()."""
-    @functools.wraps(func)
-    def wrapper(*args):
-        cwd = os.getcwd()
-        key = (cwd,) + args
-        try:
-            return wrapper._cache[key]
-        except KeyError:
-            ret = wrapper._cache[key] = func(*args)
-            return ret
-
-    wrapper._cache = {}
-
-    return wrapper
-
-
 @contextlib.contextmanager
 def clean_path_on_failure(path):
     """Cleans up the directory on an exceptional failure."""
diff --git a/tests/commands/run_test.py b/tests/commands/run_test.py
index 2426068a..e37eca64 100644
--- a/tests/commands/run_test.py
+++ b/tests/commands/run_test.py
@@ -11,9 +11,10 @@ import pytest
 import pre_commit.constants as C
 from pre_commit.commands.install_uninstall import install
 from pre_commit.commands.run import _compute_cols
-from pre_commit.commands.run import _filter_by_include_exclude
 from pre_commit.commands.run import _get_skips
 from pre_commit.commands.run import _has_unmerged_paths
+from pre_commit.commands.run import Classifier
+from pre_commit.commands.run import filter_by_include_exclude
 from pre_commit.commands.run import run
 from pre_commit.util import cmd_output
 from pre_commit.util import make_executable
@@ -748,18 +749,22 @@ def test_fail_fast(cap_out, store, repo_with_failing_hook):
     assert printed.count(b'Failing hook') == 1
 
 
+def test_classifier_removes_dne():
+    classifier = Classifier(('this_file_does_not_exist',))
+    assert classifier.filenames == []
+
+
 @pytest.fixture
 def some_filenames():
     return (
         '.pre-commit-hooks.yaml',
-        'im_a_file_that_doesnt_exist.py',
         'pre_commit/git.py',
         'pre_commit/main.py',
     )
 
 
 def test_include_exclude_base_case(some_filenames):
-    ret = _filter_by_include_exclude(some_filenames, '', '^$')
+    ret = filter_by_include_exclude(some_filenames, '', '^$')
     assert ret == [
         '.pre-commit-hooks.yaml',
         'pre_commit/git.py',
@@ -771,22 +776,22 @@ def test_include_exclude_base_case(some_filenames):
 def test_matches_broken_symlink(tmpdir):
     with tmpdir.as_cwd():
         os.symlink('does-not-exist', 'link')
-        ret = _filter_by_include_exclude({'link'}, '', '^$')
+        ret = filter_by_include_exclude({'link'}, '', '^$')
         assert ret == ['link']
 
 
 def test_include_exclude_total_match(some_filenames):
-    ret = _filter_by_include_exclude(some_filenames, r'^.*\.py$', '^$')
+    ret = filter_by_include_exclude(some_filenames, r'^.*\.py$', '^$')
     assert ret == ['pre_commit/git.py', 'pre_commit/main.py']
 
 
 def test_include_exclude_does_search_instead_of_match(some_filenames):
-    ret = _filter_by_include_exclude(some_filenames, r'\.yaml$', '^$')
+    ret = filter_by_include_exclude(some_filenames, r'\.yaml$', '^$')
     assert ret == ['.pre-commit-hooks.yaml']
 
 
 def test_include_exclude_exclude_removes_files(some_filenames):
-    ret = _filter_by_include_exclude(some_filenames, '', r'\.py$')
+    ret = filter_by_include_exclude(some_filenames, '', r'\.py$')
     assert ret == ['.pre-commit-hooks.yaml']
 
 
diff --git a/tests/util_test.py b/tests/util_test.py
index 56eb5aaa..8178bb4b 100644
--- a/tests/util_test.py
+++ b/tests/util_test.py
@@ -1,17 +1,14 @@
 from __future__ import unicode_literals
 
 import os.path
-import random
 
 import pytest
 
 from pre_commit.util import CalledProcessError
 from pre_commit.util import clean_path_on_failure
 from pre_commit.util import cmd_output
-from pre_commit.util import memoize_by_cwd
 from pre_commit.util import parse_version
 from pre_commit.util import tmpdir
-from testing.util import cwd
 
 
 def test_CalledProcessError_str():
@@ -42,37 +39,6 @@ def test_CalledProcessError_str_nooutput():
     )
 
 
-@pytest.fixture
-def memoized_by_cwd():
-    @memoize_by_cwd
-    def func(arg):
-        return arg + str(random.getrandbits(64))
-
-    return func
-
-
-def test_memoized_by_cwd_returns_same_twice_in_a_row(memoized_by_cwd):
-    ret = memoized_by_cwd('baz')
-    ret2 = memoized_by_cwd('baz')
-    assert ret is ret2
-
-
-def test_memoized_by_cwd_returns_different_for_different_args(memoized_by_cwd):
-    ret = memoized_by_cwd('baz')
-    ret2 = memoized_by_cwd('bar')
-    assert ret.startswith('baz')
-    assert ret2.startswith('bar')
-    assert ret != ret2
-
-
-def test_memoized_by_cwd_changes_with_different_cwd(memoized_by_cwd):
-    ret = memoized_by_cwd('baz')
-    with cwd('.git'):
-        ret2 = memoized_by_cwd('baz')
-
-    assert ret != ret2
-
-
 def test_clean_on_failure_noop(in_tmpdir):
     with clean_path_on_failure('foo'):
         pass