diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/UnusedTagsPass.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/UnusedTagsPass.php
index 1ebb5562986ab..ecc4d9e56356a 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/UnusedTagsPass.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/UnusedTagsPass.php
@@ -24,6 +24,7 @@ class UnusedTagsPass implements CompilerPassInterface
     private $whitelist = array(
         'cache.pool.clearer',
         'console.command',
+        'container.hot_path',
         'container.service_locator',
         'container.service_subscriber',
         'controller.service_arguments',
diff --git a/src/Symfony/Bundle/FrameworkBundle/FrameworkBundle.php b/src/Symfony/Bundle/FrameworkBundle/FrameworkBundle.php
index c9778f95fe45d..a415894e34481 100644
--- a/src/Symfony/Bundle/FrameworkBundle/FrameworkBundle.php
+++ b/src/Symfony/Bundle/FrameworkBundle/FrameworkBundle.php
@@ -43,6 +43,7 @@
 use Symfony\Component\Form\DependencyInjection\FormPass;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\Bundle\Bundle;
+use Symfony\Component\HttpKernel\KernelEvents;
 use Symfony\Component\Config\Resource\ClassExistenceResource;
 use Symfony\Component\Translation\DependencyInjection\TranslationDumperPass;
 use Symfony\Component\Translation\DependencyInjection\TranslationExtractorPass;
@@ -83,6 +84,14 @@ public function build(ContainerBuilder $container)
     {
         parent::build($container);
 
+        $hotPathEvents = array(
+            KernelEvents::REQUEST,
+            KernelEvents::CONTROLLER,
+            KernelEvents::CONTROLLER_ARGUMENTS,
+            KernelEvents::RESPONSE,
+            KernelEvents::FINISH_REQUEST,
+        );
+
         $container->addCompilerPass(new LoggerPass(), PassConfig::TYPE_BEFORE_OPTIMIZATION, -32);
         $container->addCompilerPass(new RegisterControllerArgumentLocatorsPass());
         $container->addCompilerPass(new RemoveEmptyControllerArgumentLocatorsPass(), PassConfig::TYPE_BEFORE_REMOVING);
@@ -90,7 +99,7 @@ public function build(ContainerBuilder $container)
         $container->addCompilerPass(new ProfilerPass());
         // must be registered before removing private services as some might be listeners/subscribers
         // but as late as possible to get resolved parameters
-        $container->addCompilerPass(new RegisterListenersPass(), PassConfig::TYPE_BEFORE_REMOVING);
+        $container->addCompilerPass((new RegisterListenersPass())->setHotPathEvents($hotPathEvents), PassConfig::TYPE_BEFORE_REMOVING);
         $container->addCompilerPass(new TemplatingPass());
         $this->addCompilerPassIfExists($container, AddConstraintValidatorsPass::class, PassConfig::TYPE_BEFORE_REMOVING);
         $container->addCompilerPass(new AddAnnotationsCachedReaderPass(), PassConfig::TYPE_BEFORE_REMOVING);
diff --git a/src/Symfony/Bundle/FrameworkBundle/Resources/config/services.xml b/src/Symfony/Bundle/FrameworkBundle/Resources/config/services.xml
index da0e5b55edaf8..e33382ff330a1 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Resources/config/services.xml
+++ b/src/Symfony/Bundle/FrameworkBundle/Resources/config/services.xml
@@ -9,6 +9,7 @@
 
         <service id="event_dispatcher" class="Symfony\Component\EventDispatcher\ContainerAwareEventDispatcher" public="true">
             <argument type="service" id="service_container" />
+            <tag name="container.hot_path" />
         </service>
         <service id="Symfony\Component\EventDispatcher\EventDispatcherInterface" alias="event_dispatcher" />
 
@@ -17,6 +18,7 @@
             <argument type="service" id="controller_resolver" />
             <argument type="service" id="request_stack" />
             <argument type="service" id="argument_resolver" />
+            <tag name="container.hot_path" />
         </service>
         <service id="Symfony\Component\HttpKernel\HttpKernelInterface" alias="http_kernel" />
 
diff --git a/src/Symfony/Bundle/FrameworkBundle/composer.json b/src/Symfony/Bundle/FrameworkBundle/composer.json
index 27c77d0da628e..abbc1dbef368a 100644
--- a/src/Symfony/Bundle/FrameworkBundle/composer.json
+++ b/src/Symfony/Bundle/FrameworkBundle/composer.json
@@ -22,7 +22,7 @@
         "symfony/class-loader": "~3.2",
         "symfony/dependency-injection": "~3.4|~4.0",
         "symfony/config": "~3.4|~4.0",
-        "symfony/event-dispatcher": "^3.3.1|~4.0",
+        "symfony/event-dispatcher": "^3.4-beta4|~4.0-beta4",
         "symfony/http-foundation": "^3.3.11|~4.0",
         "symfony/http-kernel": "~3.4|~4.0",
         "symfony/polyfill-mbstring": "~1.0",
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/PassConfig.php b/src/Symfony/Component/DependencyInjection/Compiler/PassConfig.php
index d06d863355363..d01385107fc92 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/PassConfig.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/PassConfig.php
@@ -89,6 +89,7 @@ public function __construct()
             )),
             new DefinitionErrorExceptionPass(),
             new CheckExceptionOnInvalidReferenceBehaviorPass(),
+            new ResolveHotPathPass(),
         ));
     }
 
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveHotPathPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveHotPathPass.php
new file mode 100644
index 0000000000000..e9147f52421b8
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveHotPathPass.php
@@ -0,0 +1,71 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\Argument\ArgumentInterface;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\DependencyInjection\Reference;
+
+/**
+ * Propagate "container.hot_path" tags to referenced services.
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+class ResolveHotPathPass extends AbstractRecursivePass
+{
+    private $tagName;
+    private $resolvedIds = array();
+
+    public function __construct($tagName = 'container.hot_path')
+    {
+        $this->tagName = $tagName;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function process(ContainerBuilder $container)
+    {
+        try {
+            parent::process($container);
+            $container->getDefinition('service_container')->clearTag($this->tagName);
+        } finally {
+            $this->resolvedIds = array();
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function processValue($value, $isRoot = false)
+    {
+        if ($value instanceof ArgumentInterface) {
+            return $value;
+        }
+        if ($value instanceof Definition && $isRoot && (isset($this->resolvedIds[$this->currentId]) || !$value->hasTag($this->tagName))) {
+            return $value;
+        }
+        if ($value instanceof Reference && ContainerBuilder::IGNORE_ON_UNINITIALIZED_REFERENCE !== $value->getInvalidBehavior() && $this->container->has($id = (string) $value)) {
+            $definition = $this->container->findDefinition($id);
+            if (!$definition->hasTag($this->tagName)) {
+                $this->resolvedIds[$id] = true;
+                $definition->addTag($this->tagName);
+                parent::processValue($definition, false);
+            }
+
+            return $value;
+        }
+
+        return parent::processValue($value, $isRoot);
+    }
+}
diff --git a/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php b/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
index 87a847d2d0526..3c239bd400a8d 100644
--- a/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
+++ b/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
@@ -63,6 +63,9 @@ class PhpDumper extends Dumper
     private $usedMethodNames;
     private $namespace;
     private $asFiles;
+    private $hotPathTag;
+    private $inlineRequires;
+    private $inlinedRequires = array();
 
     /**
      * @var ProxyDumper
@@ -108,16 +111,21 @@ public function setProxyDumper(ProxyDumper $proxyDumper)
     public function dump(array $options = array())
     {
         $this->targetDirRegex = null;
+        $this->inlinedRequires = array();
         $options = array_merge(array(
             'class' => 'ProjectServiceContainer',
             'base_class' => 'Container',
             'namespace' => '',
             'as_files' => false,
             'debug' => true,
+            'hot_path_tag' => null,
+            'inline_class_loader_parameter' => 'container.dumper.inline_class_loader',
         ), $options);
 
         $this->namespace = $options['namespace'];
         $this->asFiles = $options['as_files'];
+        $this->hotPathTag = $options['hot_path_tag'];
+        $this->inlineRequires = $this->container->hasParameter($options['inline_class_loader_parameter']) && $this->container->getParameter($options['inline_class_loader_parameter']);
         $this->initializeMethodNamesMap($options['base_class']);
 
         $this->docStar = $options['debug'] ? '*' : '';
@@ -214,6 +222,7 @@ class_alias(Container{$hash}::class, {$options['class']}::class, false);
         }
 
         $this->targetDirRegex = null;
+        $this->inlinedRequires = array();
 
         $unusedEnvs = array();
         foreach ($this->container->getEnvCounters() as $env => $use) {
@@ -257,9 +266,13 @@ private function addServiceLocalTempVariables($cId, Definition $definition, arra
 
         array_unshift($inlinedDefinitions, $definition);
 
+        $collectLineage = $this->inlineRequires && !($this->hotPathTag && $definition->hasTag($this->hotPathTag));
         $isNonLazyShared = !$this->getProxyDumper()->isProxyCandidate($definition) && $definition->isShared();
-        $calls = $behavior = array();
+        $lineage = $calls = $behavior = array();
         foreach ($inlinedDefinitions as $iDefinition) {
+            if ($collectLineage && $class = is_array($factory = $iDefinition->getFactory()) && is_string($factory[0]) ? $factory[0] : $iDefinition->getClass()) {
+                $this->collectLineage($class, $lineage);
+            }
             $this->getServiceCallsFromArguments($iDefinition->getArguments(), $calls, $behavior, $isNonLazyShared);
             $isPreInstantiation = $isNonLazyShared && $iDefinition !== $definition && !$this->hasReference($cId, $iDefinition->getMethodCalls(), true) && !$this->hasReference($cId, $iDefinition->getProperties(), true);
             $this->getServiceCallsFromArguments($iDefinition->getMethodCalls(), $calls, $behavior, $isPreInstantiation);
@@ -274,6 +287,13 @@ private function addServiceLocalTempVariables($cId, Definition $definition, arra
                 continue;
             }
 
+            if ($collectLineage && ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE !== $behavior[$id] && $this->container->has($id)
+                && $this->isTrivialInstance($iDefinition = $this->container->findDefinition($id))
+                && $class = is_array($factory = $iDefinition->getFactory()) && is_string($factory[0]) ? $factory[0] : $iDefinition->getClass()
+            ) {
+                $this->collectLineage($class, $lineage);
+            }
+
             if ($callCount > 1) {
                 $name = $this->getNextVariableName();
                 $this->referenceVariables[$id] = new Variable($name);
@@ -300,9 +320,48 @@ private function addServiceLocalTempVariables($cId, Definition $definition, arra
             $code .= "\n";
         }
 
+        if ($lineage && $lineage = array_diff_key(array_flip($lineage), $this->inlinedRequires)) {
+            $code = "\n".$code;
+
+            foreach (array_reverse($lineage) as $file => $class) {
+                $code = sprintf("        require_once %s;\n", $file).$code;
+            }
+        }
+
         return $code;
     }
 
+    private function collectLineage($class, array &$lineage)
+    {
+        if (isset($lineage[$class])) {
+            return;
+        }
+        if (!$r = $this->container->getReflectionClass($class)) {
+            return;
+        }
+        if ($this->container instanceof $class) {
+            return;
+        }
+        $file = $r->getFileName();
+        if (!$file || $this->doExport($file) === $exportedFile = $this->export($file)) {
+            return;
+        }
+
+        if ($parent = $r->getParentClass()) {
+            $this->collectLineage($parent->name, $lineage);
+        }
+
+        foreach ($r->getInterfaces() as $parent) {
+            $this->collectLineage($parent->name, $lineage);
+        }
+
+        foreach ($r->getTraits() as $parent) {
+            $this->collectLineage($parent->name, $lineage);
+        }
+
+        $lineage[$class] = substr($exportedFile, 1, -1);
+    }
+
     private function generateProxyClasses()
     {
         $definitions = $this->container->getDefinitions();
@@ -509,10 +568,15 @@ private function isTrivialInstance(Definition $definition)
                     if (!$v || ($v instanceof Reference && 'service_container' === (string) $v)) {
                         continue;
                     }
+                    if ($v instanceof Reference && $this->container->has($id = (string) $v) && $this->container->findDefinition($id)->isSynthetic()) {
+                        continue;
+                    }
                     if (!is_scalar($v) || $this->dumpValue($v) !== $this->dumpValue($v, false)) {
                         return false;
                     }
                 }
+            } elseif ($arg instanceof Reference && $this->container->has($id = (string) $arg) && $this->container->findDefinition($id)->isSynthetic()) {
+                continue;
             } elseif (!is_scalar($arg) || $this->dumpValue($arg) !== $this->dumpValue($arg, false)) {
                 return false;
             }
@@ -694,7 +758,7 @@ private function addService($id, Definition $definition, &$file = null)
             $lazyInitialization = '';
         }
 
-        $asFile = $this->asFiles && $definition->isShared();
+        $asFile = $this->asFiles && $definition->isShared() && !($this->hotPathTag && $definition->hasTag($this->hotPathTag));
         $methodName = $this->generateMethodName($id);
         if ($asFile) {
             $file = $methodName.'.php';
@@ -760,7 +824,7 @@ private function addServices()
         $definitions = $this->container->getDefinitions();
         ksort($definitions);
         foreach ($definitions as $id => $definition) {
-            if ($definition->isSynthetic() || ($this->asFiles && $definition->isShared())) {
+            if ($definition->isSynthetic() || ($this->asFiles && $definition->isShared() && !($this->hotPathTag && $definition->hasTag($this->hotPathTag)))) {
                 continue;
             }
             if ($definition->isPublic()) {
@@ -778,7 +842,7 @@ private function generateServiceFiles()
         $definitions = $this->container->getDefinitions();
         ksort($definitions);
         foreach ($definitions as $id => $definition) {
-            if (!$definition->isSynthetic() && $definition->isShared()) {
+            if (!$definition->isSynthetic() && $definition->isShared() && !($this->hotPathTag && $definition->hasTag($this->hotPathTag))) {
                 $code = $this->addService($id, $definition, $file);
                 yield $file => $code;
             }
@@ -899,6 +963,7 @@ public function __construct()
         $code .= $this->asFiles ? $this->addFileMap() : '';
         $code .= $this->addPrivateServices();
         $code .= $this->addAliases();
+        $code .= $this->addInlineRequires();
         $code .= <<<'EOF'
     }
 
@@ -1050,7 +1115,7 @@ private function addMethodMap()
         $definitions = $this->container->getDefinitions();
         ksort($definitions);
         foreach ($definitions as $id => $definition) {
-            if (!$definition->isSynthetic() && (!$this->asFiles || !$definition->isShared())) {
+            if (!$definition->isSynthetic() && (!$this->asFiles || !$definition->isShared() || ($this->hotPathTag && $definition->hasTag($this->hotPathTag)))) {
                 $code .= '            '.$this->export($id).' => '.$this->export($this->generateMethodName($id)).",\n";
             }
         }
@@ -1069,7 +1134,7 @@ private function addFileMap()
         $definitions = $this->container->getDefinitions();
         ksort($definitions);
         foreach ($definitions as $id => $definition) {
-            if (!$definition->isSynthetic() && $definition->isShared()) {
+            if (!$definition->isSynthetic() && $definition->isShared() && !($this->hotPathTag && $definition->hasTag($this->hotPathTag))) {
                 $code .= sprintf("            %s => __DIR__.'/%s.php',\n", $this->export($id), $this->generateMethodName($id));
             }
         }
@@ -1137,6 +1202,38 @@ private function addAliases()
         return $code."        );\n";
     }
 
+    private function addInlineRequires()
+    {
+        if (!$this->hotPathTag || !$this->inlineRequires) {
+            return '';
+        }
+
+        $lineage = array();
+
+        foreach ($this->container->findTaggedServiceIds($this->hotPathTag) as $id => $tags) {
+            $definition = $this->container->getDefinition($id);
+            $inlinedDefinitions = $this->getInlinedDefinitions($definition);
+            array_unshift($inlinedDefinitions, $definition);
+
+            foreach ($inlinedDefinitions as $iDefinition) {
+                if ($class = is_array($factory = $iDefinition->getFactory()) && is_string($factory[0]) ? $factory[0] : $iDefinition->getClass()) {
+                    $this->collectLineage($class, $lineage);
+                }
+            }
+        }
+
+        $code = "\n";
+
+        foreach ($lineage as $file) {
+            if (!isset($this->inlinedRequires[$file])) {
+                $this->inlinedRequires[$file] = true;
+                $code .= sprintf("        require_once %s;\n", $file);
+            }
+        }
+
+        return "\n" === $code ? '' : $code;
+    }
+
     /**
      * Adds default parameters method.
      *
@@ -1408,7 +1505,7 @@ private function getServiceCallsFromArguments(array $arguments, array &$calls, a
                 $id = (string) $argument;
 
                 if (!isset($calls[$id])) {
-                    $calls[$id] = (int) $isPreInstantiation;
+                    $calls[$id] = (int) ($isPreInstantiation && $this->container->has($id) && !$this->container->findDefinition($id)->isSynthetic());
                 }
                 if (!isset($behavior[$id])) {
                     $behavior[$id] = $argument->getInvalidBehavior();
@@ -1746,9 +1843,7 @@ private function getServiceCall($id, Reference $reference = null)
             return '$this';
         }
 
-        if ($this->container->hasDefinition($id)) {
-            $definition = $this->container->getDefinition($id);
-
+        if ($this->container->hasDefinition($id) && ($definition = $this->container->getDefinition($id)) && !$definition->isSynthetic()) {
             if (null !== $reference && ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE === $reference->getInvalidBehavior()) {
                 $code = 'null';
             } elseif ($this->isTrivialInstance($definition)) {
@@ -1756,7 +1851,7 @@ private function getServiceCall($id, Reference $reference = null)
                 if ($definition->isShared()) {
                     $code = sprintf('$this->services[\'%s\'] = %s', $id, $code);
                 }
-            } elseif ($this->asFiles && $definition->isShared()) {
+            } elseif ($this->asFiles && $definition->isShared() && !($this->hotPathTag && $definition->hasTag($this->hotPathTag))) {
                 $code = sprintf("\$this->load(__DIR__.'/%s.php')", $this->generateMethodName($id));
             } else {
                 $code = sprintf('$this->%s()', $this->generateMethodName($id));
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Compiler/ResolveHotPathPassTest.php b/src/Symfony/Component/DependencyInjection/Tests/Compiler/ResolveHotPathPassTest.php
new file mode 100644
index 0000000000000..33176159cc945
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Compiler/ResolveHotPathPassTest.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\DependencyInjection\Tests\Compiler;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\DependencyInjection\Argument\IteratorArgument;
+use Symfony\Component\DependencyInjection\Compiler\ResolveHotPathPass;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\DependencyInjection\Reference;
+
+class ResolveHotPathPassTest extends TestCase
+{
+    public function testProcess()
+    {
+        $container = new ContainerBuilder();
+
+        $container->register('foo')
+            ->addTag('container.hot_path')
+            ->addArgument(new IteratorArgument(array(new Reference('lazy'))))
+            ->addArgument(new Reference('service_container'))
+            ->addArgument(new Definition('', array(new Reference('bar'))))
+            ->addArgument(new Reference('baz', ContainerBuilder::IGNORE_ON_UNINITIALIZED_REFERENCE))
+            ->addArgument(new Reference('missing'))
+        ;
+
+        $container->register('lazy');
+        $container->register('bar');
+        $container->register('bar')->addArgument(new Reference('buz'));
+        $container->register('baz')->addArgument(new Reference('lazy'));
+        $container->register('baz')->addArgument(new Reference('lazy'));
+        $container->register('buz');
+
+        (new ResolveHotPathPass())->process($container);
+
+        $this->assertFalse($container->getDefinition('lazy')->hasTag('container.hot_path'));
+        $this->assertTrue($container->getDefinition('bar')->hasTag('container.hot_path'));
+        $this->assertTrue($container->getDefinition('buz')->hasTag('container.hot_path'));
+        $this->assertFalse($container->getDefinition('baz')->hasTag('container.hot_path'));
+        $this->assertFalse($container->getDefinition('service_container')->hasTag('container.hot_path'));
+    }
+}
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php b/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
index 3c330620c85a6..e8e4a5fe806ef 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
@@ -170,9 +170,10 @@ public function testAddService()
     public function testDumpAsFiles()
     {
         $container = include self::$fixturesPath.'/containers/container9.php';
+        $container->getDefinition('bar')->addTag('hot');
         $container->compile();
         $dumper = new PhpDumper($container);
-        $dump = print_r($dumper->dump(array('as_files' => true, 'file' => __DIR__)), true);
+        $dump = print_r($dumper->dump(array('as_files' => true, 'file' => __DIR__, 'hot_path_tag' => 'hot')), true);
         if ('\\' === DIRECTORY_SEPARATOR) {
             $dump = str_replace('\\\\Fixtures\\\\includes\\\\foo.php', '/Fixtures/includes/foo.php', $dump);
         }
@@ -798,6 +799,21 @@ public function testAlmostCircularPublic()
         $this->assertSame($foo, $foo->bar->foobar->foo);
     }
 
+    public function testHotPathOptimizations()
+    {
+        $container = include self::$fixturesPath.'/containers/container_inline_requires.php';
+        $container->setParameter('inline_requires', true);
+        $container->compile();
+        $dumper = new PhpDumper($container);
+
+        $dump = $dumper->dump(array('hot_path_tag' => 'container.hot_path', 'inline_class_loader_parameter' => 'inline_requires', 'file' => self::$fixturesPath.'/php/container_inline_requires.php'));
+        if ('\\' === DIRECTORY_SEPARATOR) {
+            $dump = str_replace("'\\\\includes\\\\HotPath\\\\", "'/includes/HotPath/", $dump);
+        }
+
+        $this->assertStringEqualsFile(self::$fixturesPath.'/php/container_inline_requires.php', $dump);
+    }
+
     public function testDumpHandlesLiteralClassWithRootNamespace()
     {
         $container = new ContainerBuilder();
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/containers/container_inline_requires.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/containers/container_inline_requires.php
new file mode 100644
index 0000000000000..1acbfdfcaf81e
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/containers/container_inline_requires.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace Symfony\Tests\InlineRequires;
+
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\DependencyInjection\Dumper\PhpDumper;
+use Symfony\Component\DependencyInjection\Reference;
+use Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath;
+
+$container = new ContainerBuilder();
+
+$container->register(HotPath\C1::class)->addTag('container.hot_path')->setPublic(true);
+$container->register(HotPath\C2::class)->addArgument(new Reference(HotPath\C3::class))->setPublic(true);
+$container->register(HotPath\C3::class);
+
+return $container;
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/C1.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/C1.php
new file mode 100644
index 0000000000000..c4934d1f13aec
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/C1.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath;
+
+class C1 extends P1
+{
+    use T1;
+}
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/C2.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/C2.php
new file mode 100644
index 0000000000000..16bce8f827e48
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/C2.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath;
+
+class C2
+{
+}
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/C3.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/C3.php
new file mode 100644
index 0000000000000..5bc6dd89fe0b2
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/C3.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath;
+
+class C3
+{
+}
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/I1.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/I1.php
new file mode 100644
index 0000000000000..7147b9d2a0230
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/I1.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath;
+
+interface I1
+{
+}
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/P1.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/P1.php
new file mode 100644
index 0000000000000..e89bc320aef50
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/P1.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath;
+
+class P1 implements I1
+{
+}
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/T1.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/T1.php
new file mode 100644
index 0000000000000..3360ace5a501b
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/includes/HotPath/T1.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath;
+
+trait T1
+{
+}
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/container_inline_requires.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/container_inline_requires.php
new file mode 100644
index 0000000000000..d3d822a27da86
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/container_inline_requires.php
@@ -0,0 +1,204 @@
+<?php
+
+use Symfony\Component\DependencyInjection\Argument\RewindableGenerator;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\DependencyInjection\Container;
+use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
+use Symfony\Component\DependencyInjection\Exception\LogicException;
+use Symfony\Component\DependencyInjection\Exception\RuntimeException;
+use Symfony\Component\DependencyInjection\ParameterBag\FrozenParameterBag;
+
+/**
+ * This class has been auto-generated
+ * by the Symfony Dependency Injection Component.
+ *
+ * @final since Symfony 3.3
+ */
+class ProjectServiceContainer extends Container
+{
+    private $parameters;
+    private $targetDirs = array();
+
+    public function __construct()
+    {
+        $dir = __DIR__;
+        for ($i = 1; $i <= 5; ++$i) {
+            $this->targetDirs[$i] = $dir = dirname($dir);
+        }
+        $this->parameters = $this->getDefaultParameters();
+
+        $this->services = array();
+        $this->normalizedIds = array(
+            'symfony\\component\\dependencyinjection\\tests\\fixtures\\includes\\hotpath\\c1' => 'Symfony\\Component\\DependencyInjection\\Tests\\Fixtures\\includes\\HotPath\\C1',
+            'symfony\\component\\dependencyinjection\\tests\\fixtures\\includes\\hotpath\\c2' => 'Symfony\\Component\\DependencyInjection\\Tests\\Fixtures\\includes\\HotPath\\C2',
+            'symfony\\component\\dependencyinjection\\tests\\fixtures\\includes\\hotpath\\c3' => 'Symfony\\Component\\DependencyInjection\\Tests\\Fixtures\\includes\\HotPath\\C3',
+        );
+        $this->methodMap = array(
+            'Symfony\\Component\\DependencyInjection\\Tests\\Fixtures\\includes\\HotPath\\C1' => 'getC1Service',
+            'Symfony\\Component\\DependencyInjection\\Tests\\Fixtures\\includes\\HotPath\\C2' => 'getC2Service',
+            'Symfony\\Component\\DependencyInjection\\Tests\\Fixtures\\includes\\HotPath\\C3' => 'getC3Service',
+        );
+        $this->privates = array(
+            'Symfony\\Component\\DependencyInjection\\Tests\\Fixtures\\includes\\HotPath\\C3' => true,
+        );
+
+        $this->aliases = array();
+
+        require_once $this->targetDirs[1].'/includes/HotPath/I1.php';
+        require_once $this->targetDirs[1].'/includes/HotPath/P1.php';
+        require_once $this->targetDirs[1].'/includes/HotPath/T1.php';
+        require_once $this->targetDirs[1].'/includes/HotPath/C1.php';
+    }
+
+    public function getRemovedIds()
+    {
+        return array(
+            'Psr\\Container\\ContainerInterface' => true,
+            'Symfony\\Component\\DependencyInjection\\ContainerInterface' => true,
+        );
+    }
+
+    public function compile()
+    {
+        throw new LogicException('You cannot compile a dumped container that was already compiled.');
+    }
+
+    public function isCompiled()
+    {
+        return true;
+    }
+
+    public function isFrozen()
+    {
+        @trigger_error(sprintf('The %s() method is deprecated since version 3.3 and will be removed in 4.0. Use the isCompiled() method instead.', __METHOD__), E_USER_DEPRECATED);
+
+        return true;
+    }
+
+    /**
+     * Gets the public 'Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C1' shared service.
+     *
+     * @return \Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C1
+     */
+    protected function getC1Service()
+    {
+        return $this->services['Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C1'] = new \Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C1();
+    }
+
+    /**
+     * Gets the public 'Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C2' shared service.
+     *
+     * @return \Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C2
+     */
+    protected function getC2Service()
+    {
+        require_once $this->targetDirs[1].'/includes/HotPath/C2.php';
+        require_once $this->targetDirs[1].'/includes/HotPath/C3.php';
+
+        $a = ${($_ = isset($this->services['Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C3']) ? $this->services['Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C3'] : $this->services['Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C3'] = new \Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C3()) && false ?: '_'};
+
+        if (isset($this->services['Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C2'])) {
+            return $this->services['Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C2'];
+        }
+
+        return $this->services['Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C2'] = new \Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C2($a);
+    }
+
+    /**
+     * Gets the private 'Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C3' shared service.
+     *
+     * @return \Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C3
+     */
+    protected function getC3Service()
+    {
+        require_once $this->targetDirs[1].'/includes/HotPath/C3.php';
+
+        return $this->services['Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C3'] = new \Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C3();
+    }
+
+    public function getParameter($name)
+    {
+        if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
+            $name = $this->normalizeParameterName($name);
+
+            if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
+                throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
+            }
+        }
+        if (isset($this->loadedDynamicParameters[$name])) {
+            return $this->loadedDynamicParameters[$name] ? $this->dynamicParameters[$name] : $this->getDynamicParameter($name);
+        }
+
+        return $this->parameters[$name];
+    }
+
+    public function hasParameter($name)
+    {
+        $name = $this->normalizeParameterName($name);
+
+        return isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters);
+    }
+
+    public function setParameter($name, $value)
+    {
+        throw new LogicException('Impossible to call set() on a frozen ParameterBag.');
+    }
+
+    public function getParameterBag()
+    {
+        if (null === $this->parameterBag) {
+            $parameters = $this->parameters;
+            foreach ($this->loadedDynamicParameters as $name => $loaded) {
+                $parameters[$name] = $loaded ? $this->dynamicParameters[$name] : $this->getDynamicParameter($name);
+            }
+            $this->parameterBag = new FrozenParameterBag($parameters);
+        }
+
+        return $this->parameterBag;
+    }
+
+    private $loadedDynamicParameters = array();
+    private $dynamicParameters = array();
+
+    /**
+     * Computes a dynamic parameter.
+     *
+     * @param string The name of the dynamic parameter to load
+     *
+     * @return mixed The value of the dynamic parameter
+     *
+     * @throws InvalidArgumentException When the dynamic parameter does not exist
+     */
+    private function getDynamicParameter($name)
+    {
+        throw new InvalidArgumentException(sprintf('The dynamic parameter "%s" must be defined.', $name));
+    }
+
+    private $normalizedParameterNames = array();
+
+    private function normalizeParameterName($name)
+    {
+        if (isset($this->normalizedParameterNames[$normalizedName = strtolower($name)]) || isset($this->parameters[$normalizedName]) || array_key_exists($normalizedName, $this->parameters)) {
+            $normalizedName = isset($this->normalizedParameterNames[$normalizedName]) ? $this->normalizedParameterNames[$normalizedName] : $normalizedName;
+            if ((string) $name !== $normalizedName) {
+                @trigger_error(sprintf('Parameter names will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since version 3.4.', $name, $normalizedName), E_USER_DEPRECATED);
+            }
+        } else {
+            $normalizedName = $this->normalizedParameterNames[$normalizedName] = (string) $name;
+        }
+
+        return $normalizedName;
+    }
+
+    /**
+     * Gets the default parameters.
+     *
+     * @return array An array of the default parameters
+     */
+    protected function getDefaultParameters()
+    {
+        return array(
+            'inline_requires' => true,
+        );
+    }
+}
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_as_files.txt b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_as_files.txt
index 4bdf469a93cdf..2cc5d35cd163f 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_as_files.txt
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_as_files.txt
@@ -13,25 +13,6 @@ return array(
     'new_factory' => true,
 );
 
-    [Container%s/getBarService.php] => <?php
-
-use Symfony\Component\DependencyInjection\Argument\RewindableGenerator;
-
-// This file has been auto-generated by the Symfony Dependency Injection Component for internal use.
-// Returns the public 'bar' shared service.
-
-$a = ${($_ = isset($this->services['foo.baz']) ? $this->services['foo.baz'] : $this->load(__DIR__.'/getFoo_BazService.php')) && false ?: '_'};
-
-if (isset($this->services['bar'])) {
-    return $this->services['bar'];
-}
-
-$this->services['bar'] = $instance = new \Bar\FooClass('foo', $a, $this->getParameter('foo_bar'));
-
-$a->configure($instance);
-
-return $instance;
-
     [Container%s/getBazService.php] => <?php
 
 use Symfony\Component\DependencyInjection\Argument\RewindableGenerator;
@@ -168,7 +149,7 @@ $this->services['foo'] = $instance = \Bar\FooClass::getInstance('foo', $a, array
 $instance->foo = 'bar';
 $instance->moo = $a;
 $instance->qux = array('bar' => 'foo is bar', 'foobar' => 'bar');
-$instance->setBar(${($_ = isset($this->services['bar']) ? $this->services['bar'] : $this->load(__DIR__.'/getBarService.php')) && false ?: '_'});
+$instance->setBar(${($_ = isset($this->services['bar']) ? $this->services['bar'] : $this->getBarService()) && false ?: '_'});
 $instance->initialize();
 sc_configure($instance);
 
@@ -329,10 +310,10 @@ class Container%s extends Container
             'request' => true,
         );
         $this->methodMap = array(
+            'bar' => 'getBarService',
             'foo_bar' => 'getFooBarService',
         );
         $this->fileMap = array(
-            'bar' => __DIR__.'/getBarService.php',
             'baz' => __DIR__.'/getBazService.php',
             'configured_service' => __DIR__.'/getConfiguredServiceService.php',
             'configured_service_simple' => __DIR__.'/getConfiguredServiceSimpleService.php',
@@ -391,6 +372,26 @@ class Container%s extends Container
         return require $file;
     }
 
+    /**
+     * Gets the public 'bar' shared service.
+     *
+     * @return \Bar\FooClass
+     */
+    protected function getBarService()
+    {
+        $a = ${($_ = isset($this->services['foo.baz']) ? $this->services['foo.baz'] : $this->load(__DIR__.'/getFoo_BazService.php')) && false ?: '_'};
+
+        if (isset($this->services['bar'])) {
+            return $this->services['bar'];
+        }
+
+        $this->services['bar'] = $instance = new \Bar\FooClass('foo', $a, $this->getParameter('foo_bar'));
+
+        $a->configure($instance);
+
+        return $instance;
+    }
+
     /**
      * Gets the public 'foo_bar' service.
      *
diff --git a/src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php b/src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php
index 0b5f5629971e2..9f9c09c528035 100644
--- a/src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php
+++ b/src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php
@@ -28,6 +28,9 @@ class RegisterListenersPass implements CompilerPassInterface
     protected $listenerTag;
     protected $subscriberTag;
 
+    private $hotPathEvents = array();
+    private $hotPathTagName;
+
     /**
      * @param string $dispatcherService Service name of the event dispatcher in processed container
      * @param string $listenerTag       Tag name used for listener
@@ -40,6 +43,14 @@ public function __construct($dispatcherService = 'event_dispatcher', $listenerTa
         $this->subscriberTag = $subscriberTag;
     }
 
+    public function setHotPathEvents(array $hotPathEvents, $tagName = 'container.hot_path')
+    {
+        $this->hotPathEvents = array_flip($hotPathEvents);
+        $this->hotPathTagName = $tagName;
+
+        return $this;
+    }
+
     public function process(ContainerBuilder $container)
     {
         if (!$container->hasDefinition($this->dispatcherService) && !$container->hasAlias($this->dispatcherService)) {
@@ -65,6 +76,10 @@ public function process(ContainerBuilder $container)
                 }
 
                 $definition->addMethodCall('addListener', array($event['event'], array(new ServiceClosureArgument(new Reference($id)), $event['method']), $priority));
+
+                if (isset($this->hotPathEvents[$event['event']])) {
+                    $container->getDefinition($id)->addTag($this->hotPathTagName);
+                }
             }
         }
 
@@ -91,6 +106,10 @@ public function process(ContainerBuilder $container)
             foreach ($extractingDispatcher->listeners as $args) {
                 $args[1] = array(new ServiceClosureArgument(new Reference($id)), $args[1]);
                 $definition->addMethodCall('addListener', $args);
+
+                if (isset($this->hotPathEvents[$args[0]])) {
+                    $container->getDefinition($id)->addTag('container.hot_path');
+                }
             }
             $extractingDispatcher->listeners = array();
         }
diff --git a/src/Symfony/Component/EventDispatcher/Tests/DependencyInjection/RegisterListenersPassTest.php b/src/Symfony/Component/EventDispatcher/Tests/DependencyInjection/RegisterListenersPassTest.php
index d46d8c591195f..dbb1aa5c57b57 100644
--- a/src/Symfony/Component/EventDispatcher/Tests/DependencyInjection/RegisterListenersPassTest.php
+++ b/src/Symfony/Component/EventDispatcher/Tests/DependencyInjection/RegisterListenersPassTest.php
@@ -141,6 +141,18 @@ public function testEventSubscriberResolvableClassName()
         $this->assertEquals($expectedCalls, $definition->getMethodCalls());
     }
 
+    public function testHotPathEvents()
+    {
+        $container = new ContainerBuilder();
+
+        $container->register('foo', SubscriberService::class)->addTag('kernel.event_subscriber', array());
+        $container->register('event_dispatcher', 'stdClass');
+
+        (new RegisterListenersPass())->setHotPathEvents(array('event'))->process($container);
+
+        $this->assertTrue($container->getDefinition('foo')->hasTag('container.hot_path'));
+    }
+
     /**
      * @expectedException \InvalidArgumentException
      * @expectedExceptionMessage You have requested a non-existent parameter "subscriber.class"
diff --git a/src/Symfony/Component/HttpKernel/Kernel.php b/src/Symfony/Component/HttpKernel/Kernel.php
index 4e53230075959..3b465dc7d5b2c 100644
--- a/src/Symfony/Component/HttpKernel/Kernel.php
+++ b/src/Symfony/Component/HttpKernel/Kernel.php
@@ -818,6 +818,7 @@ protected function dumpContainer(ConfigCache $cache, ContainerBuilder $container
             'file' => $cache->getPath(),
             'as_files' => true,
             'debug' => $this->debug,
+            'hot_path_tag' => !$this->loadClassCache ? 'container.hot_path' : null,
         ));
 
         $rootCode = array_pop($content);