diff --git a/.kokoro/functions/billing.cfg b/.kokoro/functions/billing.cfg
new file mode 100644
index 0000000000..9668c9d2cb
--- /dev/null
+++ b/.kokoro/functions/billing.cfg
@@ -0,0 +1,13 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Set the folder in which the tests are run
+env_vars: {
+    key: "PROJECT"
+    value: "functions/billing"
+}
+
+# Tell the trampoline which build file to use.
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/nodejs-docs-samples/.kokoro/build.sh"
+}
diff --git a/functions/billing/.gcloudignore b/functions/billing/.gcloudignore
new file mode 100644
index 0000000000..ccc4eb240e
--- /dev/null
+++ b/functions/billing/.gcloudignore
@@ -0,0 +1,16 @@
+# This file specifies files that are *not* uploaded to Google Cloud Platform
+# using gcloud. It follows the same syntax as .gitignore, with the addition of
+# "#!include" directives (which insert the entries of the given .gitignore-style
+# file at that point).
+#
+# For more information, run:
+#   $ gcloud topic gcloudignore
+#
+.gcloudignore
+# If you would like to upload your .git directory, .gitignore file or files
+# from your .gitignore file, remove the corresponding line
+# below:
+.git
+.gitignore
+
+node_modules
diff --git a/functions/billing/index.js b/functions/billing/index.js
new file mode 100644
index 0000000000..ffe433516d
--- /dev/null
+++ b/functions/billing/index.js
@@ -0,0 +1,156 @@
+/**
+ * Copyright 2018, Google LLC.
+ * 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.
+ */
+
+// [START functions_billing_limit]
+// [START functions_billing_stop]
+const {google} = require('googleapis');
+const {auth} = require('google-auth-library');
+
+const PROJECT_ID = process.env.GCP_PROJECT;
+const PROJECT_NAME = `projects/${PROJECT_ID}`;
+// [END functions_billing_stop]
+// [END functions_billing_limit]
+
+// [START functions_billing_slack]
+const slack = require('slack');
+
+const BOT_ACCESS_TOKEN = 'xxxx-111111111111-abcdefghidklmnopq';
+const CHANNEL = 'general';
+
+exports.notifySlack = async (data, context) => {
+  const pubsubMessage = data;
+  const pubsubAttrs = JSON.stringify(pubsubMessage.attributes);
+  const pubsubData = Buffer.from(pubsubMessage.data, 'base64').toString();
+  const budgetNotificationText = `${pubsubAttrs}, ${pubsubData}`;
+
+  const res = await slack.chat.postMessage({
+    token: BOT_ACCESS_TOKEN,
+    channel: CHANNEL,
+    text: budgetNotificationText
+  });
+  console.log(res);
+};
+// [END functions_billing_slack]
+
+// [START functions_billing_stop]
+const billing = google.cloudbilling('v1').projects;
+
+exports.stopBilling = async (data, context) => {
+  const pubsubData = JSON.parse(Buffer.from(data.data, 'base64').toString());
+  if (pubsubData.costAmount <= pubsubData.budgetAmount) {
+    return `No action necessary. (Current cost: ${pubsubData.costAmount})`;
+  }
+
+  await _setAuthCredential();
+  if (await _isBillingEnabled(PROJECT_NAME)) {
+    return _disableBillingForProject(PROJECT_NAME);
+  } else {
+    return 'Billing already disabled';
+  }
+};
+
+/**
+ * @return {Promise} Credentials set globally
+ */
+const _setAuthCredential = async () => {
+  const res = await auth.getApplicationDefault();
+
+  let client = res.credential;
+  if (client.hasScopes && !client.hasScopes()) {
+    client = client.createScoped([
+      'https://www.googleapis.com/auth/cloud-billing',
+      'https://www.googleapis.com/auth/cloud-platform'
+    ]);
+  }
+
+  // Set credential globally for all requests
+  google.options({
+    auth: client
+  });
+};
+
+/**
+ * Determine whether billing is enabled for a project
+ * @param {string} projectName Name of project to check if billing is enabled
+ * @return {bool} Whether project has billing enabled or not
+ */
+const _isBillingEnabled = async (projectName) => {
+  const res = await billing.getBillingInfo({ name: projectName });
+  return res.data.billingEnabled;
+};
+
+/**
+ * Disable billing for a project by removing its billing account
+ * @param {string} projectName Name of project disable billing on
+ * @return {string} Text containing response from disabling billing
+ */
+const _disableBillingForProject = async (projectName) => {
+  const res = await billing.updateBillingInfo({
+    name: projectName,
+    resource: { 'billingAccountName': '' } // Disable billing
+  });
+  return `Billing disabled: ${JSON.stringify(res.data)}`;
+};
+// [END functions_billing_stop]
+
+// [START functions_billing_limit]
+const compute = google.compute('v1');
+const ZONE = 'us-west1-b';
+
+exports.limitUse = async (data, context) => {
+  const pubsubData = JSON.parse(Buffer.from(data.data, 'base64').toString());
+  if (pubsubData.costAmount <= pubsubData.budgetAmount) {
+    return `No action necessary. (Current cost: ${pubsubData.costAmount})`;
+  }
+
+  await _setAuthCredential();
+  const instanceNames = await _listRunningInstances(PROJECT_ID, ZONE);
+  await _stopInstances(PROJECT_ID, ZONE, instanceNames);
+};
+
+/**
+ * @return {Promise} Array of names of running instances
+ */
+const _listRunningInstances = async (projectId, zone) => {
+  const res = await compute.instances.list({
+    project: projectId,
+    zone: zone
+  });
+
+  const instances = res.data.items || [];
+  const ranInstances = instances.filter(item => item.status === 'RUNNING');
+  return ranInstances.map(item => item.name);
+};
+
+/**
+ * @param {Array} instanceNames Names of instance to stop
+ * @return {Promise} Response from stopping instances
+ */
+const _stopInstances = async (projectId, zone, instanceNames) => {
+  if (!instanceNames.length) {
+    return 'No running instances were found.';
+  }
+  await Promise.all(instanceNames.map(instanceName => {
+    return compute.instances.stop({
+      project: projectId,
+      zone: zone,
+      instance: instanceName
+    }).then((res) => {
+      console.log('Instance stopped successfully: ' + instanceName);
+      return res.data;
+    });
+  }));
+};
+// [END functions_billing_limit]
diff --git a/functions/billing/package.json b/functions/billing/package.json
new file mode 100644
index 0000000000..465dd1066b
--- /dev/null
+++ b/functions/billing/package.json
@@ -0,0 +1,24 @@
+{
+  "name": "cloud-functions-billing",
+  "version": "0.0.1",
+  "description": "Examples of integrating Cloud Functions with billing",
+  "main": "index.js",
+  "scripts": {
+    "lint": "repo-tools lint",
+    "pretest": "npm run lint",
+    "test": "ava test/*"
+  },
+  "author": "Ace Nassri <anassri@google.com>",
+  "license": "Apache-2.0",
+  "dependencies": {
+    "google-auth-library": "^2.0.0",
+    "googleapis": "^33.0.0",
+    "slack": "^11.0.1"
+  },
+  "devDependencies": {
+    "@google-cloud/nodejs-repo-tools": "^2.2.5",
+    "ava": "^0.25.0",
+    "proxyquire": "^2.1.0",
+    "sinon": "^6.3.4"
+  }
+}
diff --git a/functions/billing/test/index.test.js b/functions/billing/test/index.test.js
new file mode 100644
index 0000000000..ef94be98de
--- /dev/null
+++ b/functions/billing/test/index.test.js
@@ -0,0 +1,144 @@
+/**
+ * Copyright 2018, Google LLC.
+ * 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.
+ */
+
+const proxyquire = require(`proxyquire`).noCallThru();
+const sinon = require(`sinon`);
+const test = require(`ava`);
+
+function getSample () {
+  const instanceListMock = [
+    { name: 'test-instance-1', status: 'RUNNING' },
+    { name: 'test-instance-2', status: 'RUNNING' }
+  ];
+
+  const listInstancesResponseMock = {
+    data: {
+      items: instanceListMock
+    }
+  };
+
+  const computeMock = {
+    instances: {
+      list: sinon.stub().returns(listInstancesResponseMock),
+      stop: sinon.stub().resolves({ data: {} })
+    }
+  };
+
+  const cloudbillingMock = {
+    projects: {
+      getBillingInfo: sinon.stub().resolves({
+        data: {
+          billingEnabled: true
+        }
+      }),
+      updateBillingInfo: sinon.stub().returns({
+        data: {}
+      })
+    }
+  };
+
+  const googleMock = {
+    cloudbilling: sinon.stub().returns(cloudbillingMock),
+    compute: sinon.stub().returns(computeMock),
+    options: sinon.stub()
+  };
+
+  const googleapisMock = {
+    google: googleMock
+  };
+
+  const slackMock = {
+    chat: {
+      postMessage: sinon.stub().returns({ data: {} })
+    }
+  };
+
+  const credentialMock = {
+    hasScopes: sinon.stub().returns(false)
+  };
+  credentialMock.createScoped = sinon.stub().returns(credentialMock);
+
+  const googleAuthMock = {
+    auth: {
+      getApplicationDefault: sinon.stub().resolves({
+        credential: credentialMock
+      })
+    }
+  };
+
+  return {
+    program: proxyquire(`../`, {
+      'google-auth-library': googleAuthMock,
+      'googleapis': googleapisMock,
+      'slack': slackMock
+    }),
+    mocks: {
+      google: googleMock,
+      googleAuth: googleAuthMock,
+      googleapis: googleapisMock,
+      compute: computeMock,
+      cloudbilling: cloudbillingMock,
+      credential: credentialMock,
+      slack: slackMock,
+      instanceList: instanceListMock
+    }
+  };
+}
+
+test(`should notify Slack when budget is exceeded`, async t => {
+  const {program, mocks} = getSample();
+
+  const jsonData = { cost: 500, budget: 400 };
+  const pubsubData = {
+    data: Buffer.from(JSON.stringify(jsonData)).toString('base64'),
+    attributes: {}
+  };
+
+  await program.notifySlack(pubsubData, null);
+
+  t.true(mocks.slack.chat.postMessage.calledOnce);
+});
+
+test(`should disable billing when budget is exceeded`, async t => {
+  const {program, mocks} = getSample();
+
+  const jsonData = { cost: 500, budget: 400 };
+  const pubsubData = {
+    data: Buffer.from(JSON.stringify(jsonData)).toString('base64'),
+    attributes: {}
+  };
+
+  await program.stopBilling(pubsubData, null);
+
+  t.true(mocks.credential.createScoped.calledOnce);
+  t.true(mocks.cloudbilling.projects.getBillingInfo.calledOnce);
+  t.true(mocks.cloudbilling.projects.updateBillingInfo.calledOnce);
+});
+
+test(`should shut down GCE instances when budget is exceeded`, async t => {
+  const {program, mocks} = getSample();
+
+  const jsonData = { cost: 500, budget: 400 };
+  const pubsubData = {
+    data: Buffer.from(JSON.stringify(jsonData)).toString('base64'),
+    attributes: {}
+  };
+
+  await program.limitUse(pubsubData, null);
+
+  t.true(mocks.credential.createScoped.calledOnce);
+  t.true(mocks.compute.instances.list.calledOnce);
+  t.is(mocks.compute.instances.stop.callCount, mocks.instanceList.length);
+});