diff --git a/functions/tips_preload/.gcloudignore b/functions/tips_preload/.gcloudignore
new file mode 100644
index 0000000000..d65708d3b0
--- /dev/null
+++ b/functions/tips_preload/.gcloudignore
@@ -0,0 +1,15 @@
+# The .gcloudignore file excludes file from upload to Cloud Build.
+# If this file is deleted, gcloud will default to .gitignore.
+#
+# https://cloud.google.com/cloud-build/docs/speeding-up-builds#gcloudignore
+# https://cloud.google.com/sdk/gcloud/reference/topic/gcloudignore
+
+# Exclude our local tests
+test/
+
+# Exclude locally vendored dependencies.
+vendor/
+
+# Exclude git history and configuration.
+.git/
+.gitignore
diff --git a/functions/tips_preload/ClassToPreload.php b/functions/tips_preload/ClassToPreload.php
new file mode 100644
index 0000000000..3483dfd946
--- /dev/null
+++ b/functions/tips_preload/ClassToPreload.php
@@ -0,0 +1,28 @@
+<?php
+/**
+ * Copyright 2021 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.
+ */
+
+namespace Google\Cloud\Samples\Functions\TipsPreload;
+
+/**
+ * Empty class to verify the preloading works.
+ * We use a new class so that we know it won't be preloaded by another class
+ * before we can check for it in "index.php".
+ */
+class ClassToPreload
+{
+    // There is nothing to be done
+}
diff --git a/functions/tips_preload/composer.json b/functions/tips_preload/composer.json
new file mode 100644
index 0000000000..2e71085f4c
--- /dev/null
+++ b/functions/tips_preload/composer.json
@@ -0,0 +1,19 @@
+{
+    "require": {
+        "google/cloud-functions-framework": "^0.7.2"
+    },
+    "config": {
+        "optimize-autoloader": true
+    },
+    "autoload": {
+        "psr-4": {
+            "Google\\Cloud\\Samples\\Functions\\TipsPreload\\": ""
+        }
+    },
+    "scripts": {
+        "start": [
+           "Composer\\Config::disableProcessTimeout",
+           "FUNCTION_TARGET=preloadDemo php -d opcache.preload=preload.php -S localhost:${PORT:-8080} vendor/bin/router.php"
+        ]
+    }
+}
diff --git a/functions/tips_preload/index.php b/functions/tips_preload/index.php
new file mode 100644
index 0000000000..c78b78d4e4
--- /dev/null
+++ b/functions/tips_preload/index.php
@@ -0,0 +1,33 @@
+<?php
+/**
+ * Copyright 2021 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_tips_preload]
+
+use Psr\Http\Message\ServerRequestInterface;
+use Google\Cloud\Samples\Functions\TipsPreload\ClassToPreload;
+
+function preloadDemo(ServerRequestInterface $request = null): string
+{
+    // Verify the class exists without making a call to the autoloader
+    $classIsPreloaded = class_exists(ClassToPreload::class, $autoload = false);
+
+    return sprintf(
+        'Class is preloaded: %s',
+        var_export($classIsPreloaded, true)
+    );
+}
+// [END functions_tips_preload]
diff --git a/functions/tips_preload/php.ini b/functions/tips_preload/php.ini
new file mode 100644
index 0000000000..9b26560020
--- /dev/null
+++ b/functions/tips_preload/php.ini
@@ -0,0 +1 @@
+opcache.preload=preload.php
diff --git a/functions/tips_preload/phpunit.xml.dist b/functions/tips_preload/phpunit.xml.dist
new file mode 100644
index 0000000000..f2dbf77ddc
--- /dev/null
+++ b/functions/tips_preload/phpunit.xml.dist
@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  Copyright 2021 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.
+-->
+<phpunit bootstrap="../../testing/bootstrap.php" convertWarningsToExceptions="false">
+    <testsuites>
+        <testsuite name="Cloud Functions preload Test Suite">
+            <directory>test</directory>
+        </testsuite>
+    </testsuites>
+    <logging>
+        <log type="coverage-clover" target="build/logs/clover.xml"/>
+    </logging>
+    <filter>
+        <whitelist>
+            <directory suffix=".php">.</directory>
+            <exclude>
+              <directory>./vendor</directory>
+            </exclude>
+        </whitelist>
+    </filter>
+</phpunit>
diff --git a/functions/tips_preload/preload.php b/functions/tips_preload/preload.php
new file mode 100644
index 0000000000..d06039c4b4
--- /dev/null
+++ b/functions/tips_preload/preload.php
@@ -0,0 +1,13 @@
+<?php
+
+require_once __DIR__ . '/vendor/autoload.php';
+
+// By running "composer dump-autoload --optimize", the classmap file contains a
+// mapping of optimized class files.
+$composerClassmap = __DIR__ . '/vendor/composer/autoload_classmap.php';
+
+$classesToPreload = require $composerClassmap;
+
+foreach ($classesToPreload as $class => $file) {
+    require_once $file;
+}
diff --git a/functions/tips_preload/test/DeployTest.php b/functions/tips_preload/test/DeployTest.php
new file mode 100644
index 0000000000..334233de1c
--- /dev/null
+++ b/functions/tips_preload/test/DeployTest.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Copyright 2021 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.
+ */
+
+declare(strict_types=1);
+
+namespace Google\Cloud\Samples\Functions\TipsPreload\Test;
+
+use Google\Cloud\TestUtils\CloudFunctionDeploymentTrait;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Class DeployTest.
+ *
+ * This test is not run by the CI system.
+ *
+ * To skip deployment of a new function, run with "GOOGLE_SKIP_DEPLOYMENT=true".
+ * To skip deletion of the tested function, run with "GOOGLE_KEEP_DEPLOYMENT=true".
+ */
+class DeployTest extends TestCase
+{
+    use CloudFunctionDeploymentTrait;
+
+    private static $entryPoint = 'preloadDemo';
+
+    public function testFunction(): void
+    {
+        // Send a request to the function.
+        $resp = $this->client->post('', [
+            // Uncomment and CURLOPT_VERBOSE debug content will be sent to stdout.
+            // 'debug' => true
+        ]);
+
+        $output = trim((string) $resp->getBody());
+
+        $this->assertEquals('200', $resp->getStatusCode());
+        $this->assertStringContainsString('Class is preloaded: true', $output);
+    }
+}
diff --git a/functions/tips_preload/test/IntegrationTest.php b/functions/tips_preload/test/IntegrationTest.php
new file mode 100644
index 0000000000..c12b29440e
--- /dev/null
+++ b/functions/tips_preload/test/IntegrationTest.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Copyright 2021 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.
+ */
+declare(strict_types=1);
+
+namespace Google\Cloud\Samples\Functions\TipsPreload\Test;
+
+use Google\Cloud\TestUtils\CloudFunctionLocalTestTrait;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Process\PhpExecutableFinder;
+
+/**
+ * Class IntegrationTest.
+ */
+class IntegrationTest extends TestCase
+{
+    use CloudFunctionLocalTestTrait;
+
+    private static $entryPoint = 'preloadDemo';
+
+    public function testFunction(): void
+    {
+        $resp = $this->client->get('/');
+        $output = trim((string) $resp->getBody());
+
+        $this->assertEquals('200', $resp->getStatusCode());
+        $this->assertStringContainsString('Class is preloaded: true', $output);
+    }
+
+    private static function doRun()
+    {
+        $phpBin = (new PhpExecutableFinder())->find();
+
+        // add opcache.preload ini
+        $phpBin .= ' -d opcache.preload=preload.php';
+
+        return self::$fn->run([], '8080', $phpBin);
+    }
+}