diff --git a/src/Symfony/Component/DependencyInjection/Dumper/XmlDumper.php b/src/Symfony/Component/DependencyInjection/Dumper/XmlDumper.php
index 38025ff3eac8c..463a3695c0f0b 100644
--- a/src/Symfony/Component/DependencyInjection/Dumper/XmlDumper.php
+++ b/src/Symfony/Component/DependencyInjection/Dumper/XmlDumper.php
@@ -22,6 +22,7 @@
  *
  * @author Fabien Potencier <fabien@symfony.com>
  * @author Martin Hasoň <martin.hason@gmail.com>
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
  *
  * @api
  */
@@ -239,6 +240,14 @@ private function convertParameters($parameters, $type, \DOMElement $parent, $key
                 } elseif ($behaviour == ContainerInterface::IGNORE_ON_INVALID_REFERENCE) {
                     $element->setAttribute('on-invalid', 'ignore');
                 }
+
+                if ( ! $value->isStrict()) {
+                    $element->setAttribute('strict', 'false');
+                }
+
+                if ($value->isLazy()) {
+                    $element->setAttribute('lazy', 'true');
+                }
             } elseif ($value instanceof Definition) {
                 $element->setAttribute('type', 'service');
                 $this->addService($value, null, $element);
diff --git a/src/Symfony/Component/DependencyInjection/Dumper/YamlDumper.php b/src/Symfony/Component/DependencyInjection/Dumper/YamlDumper.php
index 82d68008e0eeb..b4ffa323ac6fb 100644
--- a/src/Symfony/Component/DependencyInjection/Dumper/YamlDumper.php
+++ b/src/Symfony/Component/DependencyInjection/Dumper/YamlDumper.php
@@ -24,6 +24,7 @@
  * YamlDumper dumps a service container as a YAML string.
  *
  * @author Fabien Potencier <fabien@symfony.com>
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
  *
  * @api
  */
@@ -212,7 +213,15 @@ private function dumpValue($value)
 
             return $code;
         } elseif ($value instanceof Reference) {
-            return $this->getServiceCall((string) $value, $value);
+            $call = $this->getServiceCall((string) $value, $value);
+            if ($value->isLazy()) {
+                $call .= '~';
+            }
+            if ( ! $value->isStrict()) {
+                $call .= '=';
+            }
+
+            return $call;
         } elseif ($value instanceof Parameter) {
             return $this->getParameterCall((string) $value);
         } elseif (is_object($value) || is_resource($value)) {
diff --git a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
index 6f2c8eba1ada6..ebb0b28d5619c 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
@@ -25,6 +25,7 @@
  * XmlFileLoader loads XML files service definitions.
  *
  * @author Fabien Potencier <fabien@symfony.com>
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
  */
 class XmlFileLoader extends FileLoader
 {
diff --git a/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
index 71de4ac6592f6..482bab827913b 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
@@ -26,6 +26,7 @@
  * The YAML format does not support anonymous services (cf. the XML loader).
  *
  * @author Fabien Potencier <fabien@symfony.com>
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
  */
 class YamlFileLoader extends FileLoader
 {
@@ -298,14 +299,20 @@ private function resolveServices($value)
                 $invalidBehavior = ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE;
             }
 
+            $strict = true;
             if ('=' === substr($value, -1)) {
                 $value = substr($value, 0, -1);
                 $strict = false;
-            } else {
-                $strict = true;
+            }
+
+            $lazy = false;
+            if ('~' === substr($value, -1)) {
+                $value = substr($value, 0, -1);
+                $lazy = true;
             }
 
             $value = new Reference($value, $invalidBehavior, $strict);
+            $value->setLazy($lazy);
         }
 
         return $value;
diff --git a/src/Symfony/Component/DependencyInjection/Loader/schema/dic/services/services-1.0.xsd b/src/Symfony/Component/DependencyInjection/Loader/schema/dic/services/services-1.0.xsd
index 316f2d7596870..ab76a77a51227 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/schema/dic/services/services-1.0.xsd
+++ b/src/Symfony/Component/DependencyInjection/Loader/schema/dic/services/services-1.0.xsd
@@ -126,6 +126,7 @@
     <xsd:attribute name="name" type="xsd:string" />
     <xsd:attribute name="on-invalid" type="xsd:string" />
     <xsd:attribute name="strict" type="boolean" />
+    <xsd:attribute name="lazy" type="boolean" />
   </xsd:complexType>
 
   <xsd:complexType name="argument" mixed="true">
@@ -139,6 +140,7 @@
     <xsd:attribute name="index" type="xsd:integer" />
     <xsd:attribute name="on-invalid" type="xsd:string" />
     <xsd:attribute name="strict" type="boolean" />
+    <xsd:attribute name="lazy" type="boolean" />
   </xsd:complexType>
 
   <xsd:complexType name="call" mixed="true">
diff --git a/src/Symfony/Component/DependencyInjection/Reference.php b/src/Symfony/Component/DependencyInjection/Reference.php
index 1517da29885a7..8663d7155f6d1 100644
--- a/src/Symfony/Component/DependencyInjection/Reference.php
+++ b/src/Symfony/Component/DependencyInjection/Reference.php
@@ -15,6 +15,7 @@
  * Reference represents a service reference.
  *
  * @author Fabien Potencier <fabien@symfony.com>
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
  *
  * @api
  */
@@ -23,6 +24,7 @@ class Reference
     private $id;
     private $invalidBehavior;
     private $strict;
+    private $lazy = false;
 
     /**
      * Constructor.
@@ -69,4 +71,28 @@ public function isStrict()
     {
         return $this->strict;
     }
+
+    /**
+     * Whether this reference should be lazily initialized if available.
+     *
+     * @return Boolean
+     */
+    public function isLazy()
+    {
+        return $this->lazy;
+    }
+
+    /**
+     * Sets the lazily initialization status for this reference.
+     *
+     * @param Boolean $bool
+     *
+     * @return Reference
+     */
+    public function setLazy($bool)
+    {
+        $this->lazy = $bool;
+
+        return $this;
+    }
 }
diff --git a/src/Symfony/Component/DependencyInjection/SimpleXMLElement.php b/src/Symfony/Component/DependencyInjection/SimpleXMLElement.php
index d154602fd330d..9d80041fe1961 100644
--- a/src/Symfony/Component/DependencyInjection/SimpleXMLElement.php
+++ b/src/Symfony/Component/DependencyInjection/SimpleXMLElement.php
@@ -74,6 +74,11 @@ public function getArgumentsAsPhp($name, $lowercase = true)
                     }
 
                     $arguments[$key] = new Reference((string) $arg['id'], $invalidBehavior, $strict);
+
+                    if (isset($arg['lazy'])) {
+                        $arguments[$key]->setLazy(self::phpize($arg['lazy']));
+                    }
+
                     break;
                 case 'collection':
                     $arguments[$key] = $arg->getArgumentsAsPhp($name, false);
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml
index 45bc042f61906..b3fbccec989df 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml
@@ -46,5 +46,9 @@
     <service id="alias_for_foo" alias="foo" />
     <service id="another_alias_for_foo" alias="foo" public="false" />
     <service id="factory_service" factory-method="getInstance" factory-service="baz_factory" />
+    <service id="lazy_deps_service">
+        <argument type="service" id="foo" lazy="true" />
+        <argument type="service" id="bar" />
+    </service>
   </services>
 </container>
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services6.yml b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services6.yml
index eaa52bda62065..b94cffef3ae19 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services6.yml
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services6.yml
@@ -24,3 +24,5 @@ services:
         alias: foo
         public: false
     factory_service: { class: BazClass, factory_method: getInstance, factory_service: baz_factory }
+    lazy_deps_service:
+        arguments: ["@foo~", "@bar"]
\ No newline at end of file
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php b/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php
index b589ed95ac036..810855884acc8 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php
@@ -173,6 +173,10 @@ public function testLoadServices()
         $this->assertEquals('getInstance', $services['factory_service']->getFactoryMethod());
         $this->assertEquals('baz_factory', $services['factory_service']->getFactoryService());
 
+        $args = $services['lazy_deps_service']->getArguments();
+        $this->assertTrue($args[0]->isLazy());
+        $this->assertFalse($args[1]->isLazy());
+
         $aliases = $container->getAliases();
         $this->assertTrue(isset($aliases['alias_for_foo']), '->load() parses <service> elements');
         $this->assertEquals('foo', (string) $aliases['alias_for_foo'], '->load() parses aliases');
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Loader/YamlFileLoaderTest.php b/src/Symfony/Component/DependencyInjection/Tests/Loader/YamlFileLoaderTest.php
index e655d3bd8981a..2ecd5b2935b65 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Loader/YamlFileLoaderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Loader/YamlFileLoaderTest.php
@@ -128,6 +128,10 @@ public function testLoadServices()
         $this->assertEquals(array(array('setBar', array('foo', new Reference('foo'), array(true, false)))), $services['method_call2']->getMethodCalls(), '->load() parses the method_call tag');
         $this->assertEquals('baz_factory', $services['factory_service']->getFactoryService());
 
+        $args = $services['lazy_deps_service']->getArguments();
+        $this->assertTrue($args[0]->isLazy());
+        $this->assertFalse($args[1]->isLazy());
+
         $aliases = $container->getAliases();
         $this->assertTrue(isset($aliases['alias_for_foo']), '->load() parses aliases');
         $this->assertEquals('foo', (string) $aliases['alias_for_foo'], '->load() parses aliases');