diff --git a/build-system/tasks/runtime-test/runtime-test-base.js b/build-system/tasks/runtime-test/runtime-test-base.js
index 47f64dfff24c..5a7f0bc7850a 100644
--- a/build-system/tasks/runtime-test/runtime-test-base.js
+++ b/build-system/tasks/runtime-test/runtime-test-base.js
@@ -127,7 +127,7 @@ function getFiles(testType) {
 
   switch (testType) {
     case 'unit':
-      files = testConfig.commonUnitTestPaths.concat(testConfig.chaiAsPromised);
+      files = testConfig.commonUnitTestPaths;
       if (argv.files) {
         return files.concat(argv.files);
       }
@@ -147,7 +147,7 @@ function getFiles(testType) {
       return files.concat(testConfig.integrationTestPaths);
 
     case 'a4a':
-      return testConfig.chaiAsPromised.concat(testConfig.a4aTestPaths);
+      return testConfig.a4aTestPaths;
 
     default:
       throw new Error(`Test type ${testType} was not recognized`);
@@ -241,8 +241,31 @@ class RuntimeTestConfig {
       // don't overwrite existing plugins
       const plugins = [instanbulPlugin].concat(this.babelifyConfig.plugins);
 
+      /**
+       * 'chai-as-promised' contains ES6 code. This is fine for most test environments,
+       * but not for integration tests running on SauceLabs, since some browsers only
+       * support ES5 code. Therefore we instruct browserify to transpile the library.
+       *
+       * Since browserify doesn't have good support for specifying a node_module to transpile,
+       * this hack works by saying "transpile everything except for thing in node_modules
+       * called 'chai-as-promised'".
+       */
+      const babelifyChaiAsPromisedHack =
+        this.testType !== 'integration'
+          ? {}
+          : {
+              global: true,
+              ignore: [/\/node_modules\/(?!chai-as-promised\/)/],
+            };
       this.browserify.transform = [
-        ['babelify', {...this.babelifyConfig, plugins}],
+        [
+          'babelify',
+          {
+            ...this.babelifyConfig,
+            ...babelifyChaiAsPromisedHack,
+            plugins,
+          },
+        ],
       ];
     }
   }
diff --git a/build-system/test-configs/config.js b/build-system/test-configs/config.js
index dd4497b29560..18e255e4f9a2 100644
--- a/build-system/test-configs/config.js
+++ b/build-system/test-configs/config.js
@@ -73,8 +73,6 @@ const a4aTestPaths = initTestsPath.concat([
   'ads/google/a4a/test/*.js',
 ]);
 
-const chaiAsPromised = ['test/chai-as-promised/chai-as-promised.js'];
-
 const unitTestPaths = [
   'test/unit/**/*.js',
   'ads/**/test/test-*.js',
@@ -204,7 +202,6 @@ const changelogIgnoreFileTypes = /\.md|\.json|\.yaml|LICENSE|CONTRIBUTORS$/;
 /** @const  */
 module.exports = {
   a4aTestPaths,
-  chaiAsPromised,
   changelogIgnoreFileTypes,
   commonIntegrationTestPaths,
   commonUnitTestPaths,
diff --git a/extensions/amp-bind/0.1/test/integration/test-bind-impl.js b/extensions/amp-bind/0.1/test/integration/test-bind-impl.js
index f7df9d6fe2f9..5a9a068cf867 100644
--- a/extensions/amp-bind/0.1/test/integration/test-bind-impl.js
+++ b/extensions/amp-bind/0.1/test/integration/test-bind-impl.js
@@ -983,13 +983,8 @@ describe
               mystate: {mykey: 'myval'},
             });
 
-            // Integration tests may not use chai-as-promised.
-            try {
-              await bind.getStateAsync('mystate.mykey');
-              expect.fail();
-            } catch (err) {
-              expect(err).match(/#mystate/);
-            }
+            const state = bind.getStateAsync('mystate.mykey');
+            expect(state).to.eventually.rejectedWith(/#mystate/);
           });
 
           it('should not wait if the still-loading state is irrelevant', async () => {
diff --git a/test/_init_tests.js b/test/_init_tests.js
index fa8514fba6d9..2bbcf1d447e0 100644
--- a/test/_init_tests.js
+++ b/test/_init_tests.js
@@ -42,6 +42,8 @@ import PreactEnzyme from 'enzyme-adapter-preact-pure';
 import sinon from /*OK*/ 'sinon';
 import stringify from 'json-stable-stringify';
 
+chai.use(require('chai-as-promised'));
+
 // Used to print warnings for unexpected console errors.
 let that;
 let consoleErrorSandbox;
diff --git a/test/chai-as-promised/.eslintrc b/test/chai-as-promised/.eslintrc
deleted file mode 100644
index 0774a2be8c6a..000000000000
--- a/test/chai-as-promised/.eslintrc
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-  "globals": {
-    "require": false
-  }
-}
diff --git a/test/chai-as-promised/chai-as-promised.js b/test/chai-as-promised/chai-as-promised.js
deleted file mode 100644
index 378b6c1f36c2..000000000000
--- a/test/chai-as-promised/chai-as-promised.js
+++ /dev/null
@@ -1,36 +0,0 @@
-/**
- * Copyright 2017 The AMP HTML Authors. All Rights Reserved.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS-IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- *
- * NOTE: This special file is required for three reasons:
- *
- * 1. The AMP unit tests use the 'chai' v4 assertion library, which depends on
- *    'chai-as-promised' v7, a library that contains ES6 code.
- *    See https://github.com/domenic/chai-as-promised/issues/133.
- *
- * 2. We cannot use 'chai-as-promised' on Sauce labs, since some browsers only
- *    support ES5 code.
- *    See https://github.com/domenic/chai-as-promised#browsernode-compatibility.
- *
- * 3. Transpiling 'chai-as-promised' with babelify is not possible
- *    since directories under `node_modules/` are ignored by default.
- *    See https://github.com/babel/babelify/issues/53.
- *
- * We therefore include this file while running unit tests (only run on chrome),
- * but not while running integration tests (run on multiple browsers).
- * As a result, integration tests may not use `chai-as-promised.
- */
-
-chai.use(require('chai-as-promised'));