diff --git a/CHANGELOG.md b/CHANGELOG.md
index d53348f215f7..e306cecfbc08 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -82,6 +82,7 @@
 - `[tests]` Free tests from the dependency on value of FORCE_COLOR ([#6585](https://github.com/facebook/jest/pull/6585/files))
 - `[jest-diff]` Standardize filenames ([#7238](https://github.com/facebook/jest/pull/7238))
 - `[*]` Add babel plugin to make sure Jest is unaffected by fake Promise implementations ([#7225](https://github.com/facebook/jest/pull/7225))
+- `[jest-haste-map]` Standardize filenames ([#7266](https://github.com/facebook/jest/pull/7266))
 
 ### Performance
 
diff --git a/packages/jest-haste-map/src/haste_fs.js b/packages/jest-haste-map/src/HasteFS.js
similarity index 100%
rename from packages/jest-haste-map/src/haste_fs.js
rename to packages/jest-haste-map/src/HasteFS.js
diff --git a/packages/jest-haste-map/src/module_map.js b/packages/jest-haste-map/src/ModuleMap.js
similarity index 100%
rename from packages/jest-haste-map/src/module_map.js
rename to packages/jest-haste-map/src/ModuleMap.js
diff --git a/packages/jest-haste-map/src/__tests__/get_mock_name.test.js b/packages/jest-haste-map/src/__tests__/get_mock_name.test.js
index 4009cbab2e2f..939a2364c6bc 100644
--- a/packages/jest-haste-map/src/__tests__/get_mock_name.test.js
+++ b/packages/jest-haste-map/src/__tests__/get_mock_name.test.js
@@ -8,7 +8,7 @@
 'use strict';
 
 import path from 'path';
-import getMockName from '../get_mock_name';
+import getMockName from '../getMockName';
 
 describe('getMockName', () => {
   it('extracts mock name from file path', () => {
diff --git a/packages/jest-haste-map/src/__tests__/index.test.js b/packages/jest-haste-map/src/__tests__/index.test.js
index bb14132a63fb..df716c9f0c09 100644
--- a/packages/jest-haste-map/src/__tests__/index.test.js
+++ b/packages/jest-haste-map/src/__tests__/index.test.js
@@ -75,7 +75,7 @@ jest.mock('sane', () => ({
   WatchmanWatcher: mockWatcherConstructor,
 }));
 
-jest.mock('../lib/watchman_watcher.js', () => mockWatcherConstructor);
+jest.mock('../lib/WatchmanWatcher.js', () => mockWatcherConstructor);
 
 let mockChangedFiles;
 let mockFs;
@@ -1230,7 +1230,7 @@ describe('HasteMap', () => {
         } catch (error) {
           const {
             DuplicateHasteCandidatesError,
-          } = require('../module_map').default;
+          } = require('../ModuleMap').default;
           expect(error).toBeInstanceOf(DuplicateHasteCandidatesError);
           expect(error.hasteName).toBe('Pear');
           expect(error.platform).toBe('g');
diff --git a/packages/jest-haste-map/src/crawlers/__tests__/watchman.test.js b/packages/jest-haste-map/src/crawlers/__tests__/watchman.test.js
index 7f80e7dadf7e..b67b849fe840 100644
--- a/packages/jest-haste-map/src/crawlers/__tests__/watchman.test.js
+++ b/packages/jest-haste-map/src/crawlers/__tests__/watchman.test.js
@@ -11,7 +11,7 @@
 const path = require('path');
 
 jest.mock('fb-watchman', () => {
-  const normalizePathSep = require('../../lib/normalize_path_sep').default;
+  const normalizePathSep = require('../../lib/normalizePathSep').default;
   const Client = jest.fn();
   Client.prototype.command = jest.fn((args, callback) =>
     setImmediate(() => {
diff --git a/packages/jest-haste-map/src/crawlers/watchman.js b/packages/jest-haste-map/src/crawlers/watchman.js
index d8fb38c5cf2f..e0d0dce9ee73 100644
--- a/packages/jest-haste-map/src/crawlers/watchman.js
+++ b/packages/jest-haste-map/src/crawlers/watchman.js
@@ -11,7 +11,7 @@ import type {InternalHasteMap} from 'types/HasteMap';
 import type {CrawlerOptions} from '../types';
 
 import * as fastPath from '../lib/fast_path';
-import normalizePathSep from '../lib/normalize_path_sep';
+import normalizePathSep from '../lib/normalizePathSep';
 import path from 'path';
 import watchman from 'fb-watchman';
 import H from '../constants';
diff --git a/packages/jest-haste-map/src/get_mock_name.js b/packages/jest-haste-map/src/getMockName.js
similarity index 100%
rename from packages/jest-haste-map/src/get_mock_name.js
rename to packages/jest-haste-map/src/getMockName.js
diff --git a/packages/jest-haste-map/src/index.js b/packages/jest-haste-map/src/index.js
index 12b56a3c4505..f7acf0cbfee4 100644
--- a/packages/jest-haste-map/src/index.js
+++ b/packages/jest-haste-map/src/index.js
@@ -13,22 +13,22 @@ import {getSha1, worker} from './worker';
 import crypto from 'crypto';
 import EventEmitter from 'events';
 import fs from 'fs';
-import getMockName from './get_mock_name';
-import getPlatformExtension from './lib/get_platform_extension';
+import getMockName from './getMockName';
+import getPlatformExtension from './lib/getPlatformExtension';
 import H from './constants';
-import HasteFS from './haste_fs';
-import HasteModuleMap from './module_map';
+import HasteFS from './HasteFS';
+import HasteModuleMap from './ModuleMap';
 import invariant from 'invariant';
 // eslint-disable-next-line import/default
 import nodeCrawl from './crawlers/node';
-import normalizePathSep from './lib/normalize_path_sep';
+import normalizePathSep from './lib/normalizePathSep';
 import os from 'os';
 import path from 'path';
 import sane from 'sane';
 import serializer from 'jest-serializer';
 // eslint-disable-next-line import/default
 import watchmanCrawl from './crawlers/watchman';
-import WatchmanWatcher from './lib/watchman_watcher';
+import WatchmanWatcher from './lib/WatchmanWatcher';
 import * as fastPath from './lib/fast_path';
 import Worker from 'jest-worker';
 
@@ -43,7 +43,7 @@ import type {
   HasteRegExp,
   MockData,
 } from 'types/HasteMap';
-import type {SerializableModuleMap as HasteSerializableModuleMap} from './module_map';
+import type {SerializableModuleMap as HasteSerializableModuleMap} from './ModuleMap';
 
 type HType = typeof H;
 
diff --git a/packages/jest-haste-map/src/lib/watchman_watcher.js b/packages/jest-haste-map/src/lib/WatchmanWatcher.js
similarity index 100%
rename from packages/jest-haste-map/src/lib/watchman_watcher.js
rename to packages/jest-haste-map/src/lib/WatchmanWatcher.js
diff --git a/packages/jest-haste-map/src/lib/__tests__/extract_requires.test.js b/packages/jest-haste-map/src/lib/__tests__/extractRequires.test.js
similarity index 98%
rename from packages/jest-haste-map/src/lib/__tests__/extract_requires.test.js
rename to packages/jest-haste-map/src/lib/__tests__/extractRequires.test.js
index b612edcf8cdf..a6172e0dcb8e 100644
--- a/packages/jest-haste-map/src/lib/__tests__/extract_requires.test.js
+++ b/packages/jest-haste-map/src/lib/__tests__/extractRequires.test.js
@@ -9,7 +9,7 @@
  */
 'use strict';
 
-import extractRequires from '../extract_requires';
+import extractRequires from '../extractRequires';
 
 it('extracts both requires and imports from code', () => {
   const code = `
diff --git a/packages/jest-haste-map/src/lib/__tests__/get_platform_extension.test.js b/packages/jest-haste-map/src/lib/__tests__/getPlatformExtension.test.js
similarity index 92%
rename from packages/jest-haste-map/src/lib/__tests__/get_platform_extension.test.js
rename to packages/jest-haste-map/src/lib/__tests__/getPlatformExtension.test.js
index df2c4fdc2db2..3c5da8702c24 100644
--- a/packages/jest-haste-map/src/lib/__tests__/get_platform_extension.test.js
+++ b/packages/jest-haste-map/src/lib/__tests__/getPlatformExtension.test.js
@@ -9,7 +9,7 @@
 
 'use strict';
 
-import getPlatformExtension from '../get_platform_extension';
+import getPlatformExtension from '../getPlatformExtension';
 
 describe('getPlatformExtension', () => {
   it('should get platform ext', () => {
diff --git a/packages/jest-haste-map/src/lib/__tests__/normalize_path_sep.test.js b/packages/jest-haste-map/src/lib/__tests__/normalizePathSep.test.js
similarity index 82%
rename from packages/jest-haste-map/src/lib/__tests__/normalize_path_sep.test.js
rename to packages/jest-haste-map/src/lib/__tests__/normalizePathSep.test.js
index c6ed861b54a7..ab466fe6a62a 100644
--- a/packages/jest-haste-map/src/lib/__tests__/normalize_path_sep.test.js
+++ b/packages/jest-haste-map/src/lib/__tests__/normalizePathSep.test.js
@@ -13,14 +13,14 @@ describe('normalizePathSep', () => {
   it('does nothing on posix', () => {
     jest.resetModules();
     jest.mock('path', () => jest.requireActual('path').posix);
-    const normalizePathSep = require('../normalize_path_sep').default;
+    const normalizePathSep = require('../normalizePathSep').default;
     expect(normalizePathSep('foo/bar/baz.js')).toEqual('foo/bar/baz.js');
   });
 
   it('replace slashes on windows', () => {
     jest.resetModules();
     jest.mock('path', () => jest.requireActual('path').win32);
-    const normalizePathSep = require('../normalize_path_sep').default;
+    const normalizePathSep = require('../normalizePathSep').default;
     expect(normalizePathSep('foo/bar/baz.js')).toEqual('foo\\bar\\baz.js');
   });
 });
diff --git a/packages/jest-haste-map/src/lib/extract_requires.js b/packages/jest-haste-map/src/lib/extractRequires.js
similarity index 100%
rename from packages/jest-haste-map/src/lib/extract_requires.js
rename to packages/jest-haste-map/src/lib/extractRequires.js
diff --git a/packages/jest-haste-map/src/lib/get_platform_extension.js b/packages/jest-haste-map/src/lib/getPlatformExtension.js
similarity index 100%
rename from packages/jest-haste-map/src/lib/get_platform_extension.js
rename to packages/jest-haste-map/src/lib/getPlatformExtension.js
diff --git a/packages/jest-haste-map/src/lib/normalize_path_sep.js b/packages/jest-haste-map/src/lib/normalizePathSep.js
similarity index 100%
rename from packages/jest-haste-map/src/lib/normalize_path_sep.js
rename to packages/jest-haste-map/src/lib/normalizePathSep.js
diff --git a/packages/jest-haste-map/src/worker.js b/packages/jest-haste-map/src/worker.js
index 53bc98be296d..acf575098e8f 100644
--- a/packages/jest-haste-map/src/worker.js
+++ b/packages/jest-haste-map/src/worker.js
@@ -14,7 +14,7 @@ import path from 'path';
 import fs from 'graceful-fs';
 import blacklist from './blacklist';
 import H from './constants';
-import extractRequires from './lib/extract_requires';
+import extractRequires from './lib/extractRequires';
 
 const PACKAGE_JSON = path.sep + 'package.json';