diff --git a/src/Symfony/Component/DependencyInjection/CHANGELOG.md b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
index 49e140de11..4232369e2e 100644
--- a/src/Symfony/Component/DependencyInjection/CHANGELOG.md
+++ b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
@@ -4,6 +4,7 @@ CHANGELOG
 3.4.0
 -----
 
+ * added support for ignore-on-uninitialized references
  * deprecated service auto-registration while autowiring
  * deprecated the ability to check for the initialization of a private service with the `Container::initialized()` method
  * deprecated support for top-level anonymous services in XML
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/AnalyzeServiceReferencesPass.php b/src/Symfony/Component/DependencyInjection/Compiler/AnalyzeServiceReferencesPass.php
index 3a375f3516..99eed81fcc 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/AnalyzeServiceReferencesPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/AnalyzeServiceReferencesPass.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\DependencyInjection\Compiler;
 
 use Symfony\Component\DependencyInjection\Argument\ArgumentInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\ExpressionLanguage;
 use Symfony\Component\DependencyInjection\Reference;
@@ -96,7 +97,8 @@ class AnalyzeServiceReferencesPass extends AbstractRecursivePass implements Repe
                 $this->getDefinitionId((string) $value),
                 $targetDefinition,
                 $value,
-                $this->lazy || ($targetDefinition && $targetDefinition->isLazy())
+                $this->lazy || ($targetDefinition && $targetDefinition->isLazy()),
+                ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE === $value->getInvalidBehavior()
             );
 
             return $value;
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/CheckExceptionOnInvalidReferenceBehaviorPass.php b/src/Symfony/Component/DependencyInjection/Compiler/CheckExceptionOnInvalidReferenceBehaviorPass.php
index 35fb325e74..7ffedd3dc0 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/CheckExceptionOnInvalidReferenceBehaviorPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/CheckExceptionOnInvalidReferenceBehaviorPass.php
@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\DependencyInjection\Compiler;
 
+use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
 use Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\DependencyInjection\Reference;
@@ -24,14 +25,16 @@ class CheckExceptionOnInvalidReferenceBehaviorPass extends AbstractRecursivePass
 {
     protected function processValue($value, $isRoot = false)
     {
-        if ($value instanceof Reference && ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE === $value->getInvalidBehavior()) {
-            $destId = (string) $value;
-
-            if (!$this->container->has($destId)) {
-                throw new ServiceNotFoundException($destId, $this->currentId);
-            }
+        if (!$value instanceof Reference) {
+            return parent::processValue($value, $isRoot);
+        }
+        if (ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE === $value->getInvalidBehavior() && !$this->container->has($id = (string) $value)) {
+            throw new ServiceNotFoundException($id, $this->currentId);
+        }
+        if (ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE === $value->getInvalidBehavior() && $this->container->has($id = (string) $value) && !$this->container->findDefinition($id)->isShared()) {
+            throw new InvalidArgumentException(sprintf('Invalid ignore-on-uninitialized reference found in service "%s": target service "%s" is not shared.', $this->currentId, $id));
         }
 
-        return parent::processValue($value, $isRoot);
+        return $value;
     }
 }
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/InlineServiceDefinitionsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/InlineServiceDefinitionsPass.php
index f2ef363c83..240e1ab655 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/InlineServiceDefinitionsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/InlineServiceDefinitionsPass.php
@@ -96,6 +96,9 @@ class InlineServiceDefinitionsPass extends AbstractRecursivePass implements Repe
 
         $ids = array();
         foreach ($graph->getNode($id)->getInEdges() as $edge) {
+            if ($edge->isWeak()) {
+                return false;
+            }
             $ids[] = $edge->getSourceNode()->getId();
         }
 
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php b/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php
index f8dba86a0b..8c81452b31 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php
@@ -74,6 +74,9 @@ class RegisterServiceSubscribersPass extends AbstractRecursivePass
             if ($optionalBehavior = '?' === $type[0]) {
                 $type = substr($type, 1);
                 $optionalBehavior = ContainerInterface::IGNORE_ON_INVALID_REFERENCE;
+            } elseif ($optionalBehavior = '!' === $type[0]) {
+                $type = substr($type, 1);
+                $optionalBehavior = ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE;
             }
             if (is_int($key)) {
                 $key = $type;
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/RemoveUnusedDefinitionsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/RemoveUnusedDefinitionsPass.php
index 79a2600d8f..a8a01be6d5 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/RemoveUnusedDefinitionsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/RemoveUnusedDefinitionsPass.php
@@ -50,6 +50,9 @@ class RemoveUnusedDefinitionsPass implements RepeatablePassInterface
                 $referencingAliases = array();
                 $sourceIds = array();
                 foreach ($edges as $edge) {
+                    if ($edge->isWeak()) {
+                        continue;
+                    }
                     $node = $edge->getSourceNode();
                     $sourceIds[] = $node->getId();
 
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ServiceReferenceGraph.php b/src/Symfony/Component/DependencyInjection/Compiler/ServiceReferenceGraph.php
index 193a37e20b..3a6f03ee6d 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ServiceReferenceGraph.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ServiceReferenceGraph.php
@@ -20,6 +20,8 @@ use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
  * it themselves which improves performance quite a lot.
  *
  * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ *
+ * @final since version 3.4
  */
 class ServiceReferenceGraph
 {
@@ -85,23 +87,16 @@ class ServiceReferenceGraph
      * @param string $destValue
      * @param string $reference
      * @param bool   $lazy
+     * @param bool   $weak
      */
-    public function connect($sourceId, $sourceValue, $destId, $destValue = null, $reference = null/*, bool $lazy = false*/)
+    public function connect($sourceId, $sourceValue, $destId, $destValue = null, $reference = null/*, bool $lazy = false, bool $weak = false*/)
     {
-        if (func_num_args() >= 6) {
-            $lazy = func_get_arg(5);
-        } else {
-            if (__CLASS__ !== get_class($this)) {
-                $r = new \ReflectionMethod($this, __FUNCTION__);
-                if (__CLASS__ !== $r->getDeclaringClass()->getName()) {
-                    @trigger_error(sprintf('Method %s() will have a 6th `bool $lazy = false` argument in version 4.0. Not defining it is deprecated since 3.3.', __METHOD__), E_USER_DEPRECATED);
-                }
-            }
-            $lazy = false;
-        }
+        $lazy = func_num_args() >= 6 ? func_get_arg(5) : false;
+        $weak = func_num_args() >= 7 ? func_get_arg(6) : false;
+
         $sourceNode = $this->createNode($sourceId, $sourceValue);
         $destNode = $this->createNode($destId, $destValue);
-        $edge = new ServiceReferenceGraphEdge($sourceNode, $destNode, $reference, $lazy);
+        $edge = new ServiceReferenceGraphEdge($sourceNode, $destNode, $reference, $lazy, $weak);
 
         $sourceNode->addOutEdge($edge);
         $destNode->addInEdge($edge);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ServiceReferenceGraphEdge.php b/src/Symfony/Component/DependencyInjection/Compiler/ServiceReferenceGraphEdge.php
index 17dd5d9559..5b8256977f 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ServiceReferenceGraphEdge.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ServiceReferenceGraphEdge.php
@@ -24,19 +24,22 @@ class ServiceReferenceGraphEdge
     private $destNode;
     private $value;
     private $lazy;
+    private $weak;
 
     /**
      * @param ServiceReferenceGraphNode $sourceNode
      * @param ServiceReferenceGraphNode $destNode
      * @param string                    $value
      * @param bool                      $lazy
+     * @param bool                      $weak
      */
-    public function __construct(ServiceReferenceGraphNode $sourceNode, ServiceReferenceGraphNode $destNode, $value = null, $lazy = false)
+    public function __construct(ServiceReferenceGraphNode $sourceNode, ServiceReferenceGraphNode $destNode, $value = null, $lazy = false, $weak = false)
     {
         $this->sourceNode = $sourceNode;
         $this->destNode = $destNode;
         $this->value = $value;
         $this->lazy = $lazy;
+        $this->weak = $weak;
     }
 
     /**
@@ -78,4 +81,14 @@ class ServiceReferenceGraphEdge
     {
         return $this->lazy;
     }
+
+    /**
+     * Returns true if the edge is weak, meaning it shouldn't prevent removing the target service.
+     *
+     * @return bool
+     */
+    public function isWeak()
+    {
+        return $this->weak;
+    }
 }
diff --git a/src/Symfony/Component/DependencyInjection/Container.php b/src/Symfony/Component/DependencyInjection/Container.php
index 30bf1a0a6c..ac423bd4a4 100644
--- a/src/Symfony/Component/DependencyInjection/Container.php
+++ b/src/Symfony/Component/DependencyInjection/Container.php
@@ -23,26 +23,15 @@ use Symfony\Component\DependencyInjection\ParameterBag\FrozenParameterBag;
  * Container is a dependency injection container.
  *
  * It gives access to object instances (services).
- *
  * Services and parameters are simple key/pair stores.
- *
- * Parameter and service keys are case insensitive.
- *
- * A service can also be defined by creating a method named
- * getXXXService(), where XXX is the camelized version of the id:
- *
- * <ul>
- *   <li>request -> getRequestService()</li>
- *   <li>mysql_session_storage -> getMysqlSessionStorageService()</li>
- *   <li>symfony.mysql_session_storage -> getSymfony_MysqlSessionStorageService()</li>
- * </ul>
- *
- * The container can have three possible behaviors when a service does not exist:
+ * The container can have four possible behaviors when a service
+ * does not exist (or is not initialized for the last case):
  *
  *  * EXCEPTION_ON_INVALID_REFERENCE: Throws an exception (the default)
  *  * NULL_ON_INVALID_REFERENCE:      Returns null
  *  * IGNORE_ON_INVALID_REFERENCE:    Ignores the wrapping command asking for the reference
  *                                    (for instance, ignore a setter if the service does not exist)
+ *  * IGNORE_ON_UNINITIALIZED_REFERENCE: Ignores/returns null for uninitialized services or invalid references
  *
  * @author Fabien Potencier <fabien@symfony.com>
  * @author Johannes M. Schmitt <schmittjoh@gmail.com>
@@ -304,9 +293,9 @@ class Container implements ResettableContainerInterface
 
             try {
                 if (isset($this->fileMap[$id])) {
-                    return $this->load($this->fileMap[$id]);
+                    return self::IGNORE_ON_UNINITIALIZED_REFERENCE === $invalidBehavior ? null : $this->load($this->fileMap[$id]);
                 } elseif (isset($this->methodMap[$id])) {
-                    return $this->{$this->methodMap[$id]}();
+                    return self::IGNORE_ON_UNINITIALIZED_REFERENCE === $invalidBehavior ? null : $this->{$this->methodMap[$id]}();
                 } elseif (--$i && $id !== $normalizedId = $this->normalizeId($id)) {
                     $id = $normalizedId;
                     continue;
@@ -315,7 +304,7 @@ class Container implements ResettableContainerInterface
                     // and only when the dumper has not generated the method map (otherwise the method map is considered to be fully populated by the dumper)
                     @trigger_error('Generating a dumped container without populating the method map is deprecated since 3.2 and will be unsupported in 4.0. Update your dumper to generate the method map.', E_USER_DEPRECATED);
 
-                    return $this->{$method}();
+                    return self::IGNORE_ON_UNINITIALIZED_REFERENCE === $invalidBehavior ? null : $this->{$method}();
                 }
 
                 break;
diff --git a/src/Symfony/Component/DependencyInjection/ContainerBuilder.php b/src/Symfony/Component/DependencyInjection/ContainerBuilder.php
index 683f8777e5..2b8dfd6a3e 100644
--- a/src/Symfony/Component/DependencyInjection/ContainerBuilder.php
+++ b/src/Symfony/Component/DependencyInjection/ContainerBuilder.php
@@ -565,6 +565,9 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
     {
         $id = $this->normalizeId($id);
 
+        if (ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE === $invalidBehavior) {
+            return parent::get($id, $invalidBehavior);
+        }
         if ($service = parent::get($id, ContainerInterface::NULL_ON_INVALID_REFERENCE)) {
             return $service;
         }
@@ -1160,6 +1163,11 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
                             continue 2;
                         }
                     }
+                    foreach (self::getInitializedConditionals($v) as $s) {
+                        if (!$this->get($s, ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE)) {
+                            continue 2;
+                        }
+                    }
 
                     yield $k => $this->resolveServices($v);
                 }
@@ -1171,6 +1179,11 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
                             continue 2;
                         }
                     }
+                    foreach (self::getInitializedConditionals($v) as $s) {
+                        if (!$this->get($s, ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE)) {
+                            continue 2;
+                        }
+                    }
 
                     ++$count;
                 }
@@ -1397,6 +1410,8 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
      * @param mixed $value An array of conditionals to return
      *
      * @return array An array of Service conditionals
+     *
+     * @internal since version 3.4
      */
     public static function getServiceConditionals($value)
     {
@@ -1413,6 +1428,30 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
         return $services;
     }
 
+    /**
+     * Returns the initialized conditionals.
+     *
+     * @param mixed $value An array of conditionals to return
+     *
+     * @return array An array of uninitialized conditionals
+     *
+     * @internal
+     */
+    public static function getInitializedConditionals($value)
+    {
+        $services = array();
+
+        if (is_array($value)) {
+            foreach ($value as $v) {
+                $services = array_unique(array_merge($services, self::getInitializedConditionals($v)));
+            }
+        } elseif ($value instanceof Reference && $value->getInvalidBehavior() === ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE) {
+            $services[] = (string) $value;
+        }
+
+        return $services;
+    }
+
     /**
      * Computes a reasonably unique hash of a value.
      *
@@ -1465,13 +1504,16 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
 
     private function callMethod($service, $call)
     {
-        $services = self::getServiceConditionals($call[1]);
-
-        foreach ($services as $s) {
+        foreach (self::getServiceConditionals($call[1]) as $s) {
             if (!$this->has($s)) {
                 return;
             }
         }
+        foreach (self::getInitializedConditionals($call[1]) as $s) {
+            if (!$this->get($s, ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE)) {
+                return;
+            }
+        }
 
         call_user_func_array(array($service, $call[0]), $this->resolveServices($this->getParameterBag()->unescapeValue($this->getParameterBag()->resolveValue($call[1]))));
     }
diff --git a/src/Symfony/Component/DependencyInjection/ContainerInterface.php b/src/Symfony/Component/DependencyInjection/ContainerInterface.php
index cfbc828722..2274ec7bb3 100644
--- a/src/Symfony/Component/DependencyInjection/ContainerInterface.php
+++ b/src/Symfony/Component/DependencyInjection/ContainerInterface.php
@@ -27,6 +27,7 @@ interface ContainerInterface extends PsrContainerInterface
     const EXCEPTION_ON_INVALID_REFERENCE = 1;
     const NULL_ON_INVALID_REFERENCE = 2;
     const IGNORE_ON_INVALID_REFERENCE = 3;
+    const IGNORE_ON_UNINITIALIZED_REFERENCE = 4;
 
     /**
      * Sets a service.
diff --git a/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php b/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
index 49cd09f02a..49e90a4115 100644
--- a/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
+++ b/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
@@ -277,7 +277,7 @@ EOF;
                 if (ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE === $behavior[$id]) {
                     $code .= sprintf($template, $name, $this->getServiceCall($id));
                 } else {
-                    $code .= sprintf($template, $name, $this->getServiceCall($id, new Reference($id, ContainerInterface::NULL_ON_INVALID_REFERENCE)));
+                    $code .= sprintf($template, $name, $this->getServiceCall($id, new Reference($id, $behavior[$id])));
                 }
             }
         }
@@ -1295,12 +1295,14 @@ EOF;
      */
     private function getServiceConditionals($value)
     {
-        if (!$services = ContainerBuilder::getServiceConditionals($value)) {
-            return null;
-        }
-
         $conditions = array();
-        foreach ($services as $service) {
+        foreach (ContainerBuilder::getInitializedConditionals($value) as $service) {
+            if (!$this->container->hasDefinition($service)) {
+                return 'false';
+            }
+            $conditions[] = sprintf("isset(\$this->services['%s'])", $service);
+        }
+        foreach (ContainerBuilder::getServiceConditionals($value) as $service) {
             if ($this->container->hasDefinition($service) && !$this->container->getDefinition($service)->isPublic()) {
                 continue;
             }
@@ -1335,8 +1337,8 @@ EOF;
                 }
                 if (!isset($behavior[$id])) {
                     $behavior[$id] = $argument->getInvalidBehavior();
-                } elseif (ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE !== $behavior[$id]) {
-                    $behavior[$id] = $argument->getInvalidBehavior();
+                } else {
+                    $behavior[$id] = min($behavior[$id], $argument->getInvalidBehavior());
                 }
 
                 ++$calls[$id];
@@ -1665,7 +1667,9 @@ EOF;
             return '$this';
         }
 
-        if ($this->asFiles && $this->container->hasDefinition($id)) {
+        if (null !== $reference && ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE === $reference->getInvalidBehavior()) {
+            $code = 'null';
+        } elseif ($this->asFiles && $this->container->hasDefinition($id)) {
             if ($this->container->getDefinition($id)->isShared()) {
                 $code = sprintf("\$this->load(__DIR__.'/%s.php')", $this->generateMethodName($id));
             } else {
diff --git a/src/Symfony/Component/DependencyInjection/Dumper/XmlDumper.php b/src/Symfony/Component/DependencyInjection/Dumper/XmlDumper.php
index c6b3be06a1..2bfefeb2d1 100644
--- a/src/Symfony/Component/DependencyInjection/Dumper/XmlDumper.php
+++ b/src/Symfony/Component/DependencyInjection/Dumper/XmlDumper.php
@@ -309,6 +309,8 @@ class XmlDumper extends Dumper
                     $element->setAttribute('on-invalid', 'null');
                 } elseif ($behaviour == ContainerInterface::IGNORE_ON_INVALID_REFERENCE) {
                     $element->setAttribute('on-invalid', 'ignore');
+                } elseif ($behaviour == ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE) {
+                    $element->setAttribute('on-invalid', 'ignore_uninitialized');
                 }
             } elseif ($value instanceof Definition) {
                 $element->setAttribute('type', 'service');
diff --git a/src/Symfony/Component/DependencyInjection/Dumper/YamlDumper.php b/src/Symfony/Component/DependencyInjection/Dumper/YamlDumper.php
index 76f97315c7..d8f07edc08 100644
--- a/src/Symfony/Component/DependencyInjection/Dumper/YamlDumper.php
+++ b/src/Symfony/Component/DependencyInjection/Dumper/YamlDumper.php
@@ -304,8 +304,12 @@ class YamlDumper extends Dumper
      */
     private function getServiceCall($id, Reference $reference = null)
     {
-        if (null !== $reference && ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE !== $reference->getInvalidBehavior()) {
-            return sprintf('@?%s', $id);
+        if (null !== $reference) {
+            switch ($reference->getInvalidBehavior()) {
+                case ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE: break;
+                case ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE: return sprintf('@!%s', $id);
+                default: return sprintf('@?%s', $id);
+            }
         }
 
         return sprintf('@%s', $id);
diff --git a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
index 0a5f9593d4..a5ee960a70 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
@@ -492,6 +492,8 @@ class XmlFileLoader extends FileLoader
             $invalidBehavior = ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE;
             if ('ignore' == $onInvalid) {
                 $invalidBehavior = ContainerInterface::IGNORE_ON_INVALID_REFERENCE;
+            } elseif ('ignore_uninitialized' == $onInvalid) {
+                $invalidBehavior = ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE;
             } elseif ('null' == $onInvalid) {
                 $invalidBehavior = ContainerInterface::NULL_ON_INVALID_REFERENCE;
             }
diff --git a/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
index 8a1c51f4e6..b57ead2c89 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
@@ -758,6 +758,9 @@ class YamlFileLoader extends FileLoader
             if (0 === strpos($value, '@@')) {
                 $value = substr($value, 1);
                 $invalidBehavior = null;
+            } elseif (0 === strpos($value, '@!')) {
+                $value = substr($value, 2);
+                $invalidBehavior = ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE;
             } elseif (0 === strpos($value, '@?')) {
                 $value = substr($value, 2);
                 $invalidBehavior = ContainerInterface::IGNORE_ON_INVALID_REFERENCE;
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 aad40ac631..0be8658e3d 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
@@ -266,6 +266,7 @@
       <xsd:enumeration value="null" />
       <xsd:enumeration value="ignore" />
       <xsd:enumeration value="exception" />
+      <xsd:enumeration value="ignore_uninitialized" />
     </xsd:restriction>
   </xsd:simpleType>
 
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Compiler/CheckExceptionOnInvalidReferenceBehaviorPassTest.php b/src/Symfony/Component/DependencyInjection/Tests/Compiler/CheckExceptionOnInvalidReferenceBehaviorPassTest.php
index 65a782a4a8..dc20b39bc4 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Compiler/CheckExceptionOnInvalidReferenceBehaviorPassTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Compiler/CheckExceptionOnInvalidReferenceBehaviorPassTest.php
@@ -67,6 +67,27 @@ class CheckExceptionOnInvalidReferenceBehaviorPassTest extends TestCase
         $this->process($container);
     }
 
+    /**
+     * @expectedException \Symfony\Component\DependencyInjection\Exception\InvalidArgumentException
+     * @expectedExceptionMessage Invalid ignore-on-uninitialized reference found in service
+     */
+    public function testProcessThrowsExceptionOnNonSharedUninitializedReference()
+    {
+        $container = new ContainerBuilder();
+
+        $container
+            ->register('a', 'stdClass')
+            ->addArgument(new Reference('b', $container::IGNORE_ON_UNINITIALIZED_REFERENCE))
+        ;
+
+        $container
+            ->register('b', 'stdClass')
+            ->setShared(false)
+        ;
+
+        $this->process($container);
+    }
+
     private function process(ContainerBuilder $container)
     {
         $pass = new CheckExceptionOnInvalidReferenceBehaviorPass();
diff --git a/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php b/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php
index 895e035185..54e3227d23 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php
@@ -1098,6 +1098,38 @@ class ContainerBuilderTest extends TestCase
         $this->assertSame($container->get('bar_service'), $foo->get('bar'));
     }
 
+    public function testUninitializedReference()
+    {
+        $container = include __DIR__.'/Fixtures/containers/container_uninitialized_ref.php';
+        $container->compile();
+
+        $bar = $container->get('bar');
+
+        $this->assertNull($bar->foo1);
+        $this->assertNull($bar->foo2);
+        $this->assertNull($bar->foo3);
+        $this->assertNull($bar->closures[0]());
+        $this->assertNull($bar->closures[1]());
+        $this->assertNull($bar->closures[2]());
+        $this->assertSame(array(), iterator_to_array($bar->iter));
+
+        $container = include __DIR__.'/Fixtures/containers/container_uninitialized_ref.php';
+        $container->compile();
+
+        $container->get('foo1');
+        $container->get('baz');
+
+        $bar = $container->get('bar');
+
+        $this->assertEquals(new \stdClass(), $bar->foo1);
+        $this->assertNull($bar->foo2);
+        $this->assertEquals(new \stdClass(), $bar->foo3);
+        $this->assertEquals(new \stdClass(), $bar->closures[0]());
+        $this->assertNull($bar->closures[1]());
+        $this->assertEquals(new \stdClass(), $bar->closures[2]());
+        $this->assertEquals(array('foo1' => new \stdClass(), 'foo3' => new \stdClass()), iterator_to_array($bar->iter));
+    }
+
     public function testRegisterForAutoconfiguration()
     {
         $container = new ContainerBuilder();
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php b/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
index 338d7b5bb3..62213ee280 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
@@ -631,6 +631,44 @@ class PhpDumperTest extends TestCase
         $this->assertStringEqualsFile(self::$fixturesPath.'/php/services_private_in_expression.php', $dumper->dump());
     }
 
+    public function testUninitializedReference()
+    {
+        $container = include self::$fixturesPath.'/containers/container_uninitialized_ref.php';
+        $container->compile();
+        $dumper = new PhpDumper($container);
+
+        $this->assertStringEqualsFile(self::$fixturesPath.'/php/services_uninitialized_ref.php', $dumper->dump(array('class' => 'Symfony_DI_PhpDumper_Test_Uninitialized_Reference')));
+
+        require self::$fixturesPath.'/php/services_uninitialized_ref.php';
+
+        $container = new \Symfony_DI_PhpDumper_Test_Uninitialized_Reference();
+
+        $bar = $container->get('bar');
+
+        $this->assertNull($bar->foo1);
+        $this->assertNull($bar->foo2);
+        $this->assertNull($bar->foo3);
+        $this->assertNull($bar->closures[0]());
+        $this->assertNull($bar->closures[1]());
+        $this->assertNull($bar->closures[2]());
+        $this->assertSame(array(), iterator_to_array($bar->iter));
+
+        $container = new \Symfony_DI_PhpDumper_Test_Uninitialized_Reference();
+
+        $container->get('foo1');
+        $container->get('baz');
+
+        $bar = $container->get('bar');
+
+        $this->assertEquals(new \stdClass(), $bar->foo1);
+        $this->assertNull($bar->foo2);
+        $this->assertEquals(new \stdClass(), $bar->foo3);
+        $this->assertEquals(new \stdClass(), $bar->closures[0]());
+        $this->assertNull($bar->closures[1]());
+        $this->assertEquals(new \stdClass(), $bar->closures[2]());
+        $this->assertEquals(array('foo1' => new \stdClass(), 'foo3' => new \stdClass()), iterator_to_array($bar->iter));
+    }
+
     public function testDumpHandlesLiteralClassWithRootNamespace()
     {
         $container = new ContainerBuilder();
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Dumper/XmlDumperTest.php b/src/Symfony/Component/DependencyInjection/Tests/Dumper/XmlDumperTest.php
index 3ac6628b73..8a34a2b19a 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Dumper/XmlDumperTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Dumper/XmlDumperTest.php
@@ -12,8 +12,12 @@
 namespace Symfony\Component\DependencyInjection\Tests\Dumper;
 
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\Config\FileLocator;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\DependencyInjection\Dumper\XmlDumper;
+use Symfony\Component\DependencyInjection\Loader\XmlFileLoader;
+use Symfony\Component\DependencyInjection\Reference;
 
 class XmlDumperTest extends TestCase
 {
@@ -184,6 +188,18 @@ class XmlDumperTest extends TestCase
         $this->assertEquals(file_get_contents(self::$fixturesPath.'/xml/services24.xml'), $dumper->dump());
     }
 
+    public function testDumpLoad()
+    {
+        $container = new ContainerBuilder();
+        $loader = new XmlFileLoader($container, new FileLocator(self::$fixturesPath.'/xml'));
+        $loader->load('services_dump_load.xml');
+
+        $this->assertEquals(array(new Reference('bar', ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE)), $container->getDefinition('foo')->getArguments());
+
+        $dumper = new XmlDumper($container);
+        $this->assertStringEqualsFile(self::$fixturesPath.'/xml/services_dump_load.xml', $dumper->dump());
+    }
+
     public function testDumpAbstractServices()
     {
         $container = include self::$fixturesPath.'/containers/container_abstract.php';
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Dumper/YamlDumperTest.php b/src/Symfony/Component/DependencyInjection/Tests/Dumper/YamlDumperTest.php
index 968385633b..85ce181461 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Dumper/YamlDumperTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Dumper/YamlDumperTest.php
@@ -14,9 +14,11 @@ namespace Symfony\Component\DependencyInjection\Tests\Dumper;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\Dumper\YamlDumper;
 use Symfony\Component\DependencyInjection\Loader\YamlFileLoader;
+use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\Yaml\Yaml;
 use Symfony\Component\Yaml\Parser;
 
@@ -73,6 +75,8 @@ class YamlDumperTest extends TestCase
         $loader = new YamlFileLoader($container, new FileLocator(self::$fixturesPath.'/yaml'));
         $loader->load('services_dump_load.yml');
 
+        $this->assertEquals(array(new Reference('bar', ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE)), $container->getDefinition('foo')->getArguments());
+
         $dumper = new YamlDumper($container);
         $this->assertStringEqualsFile(self::$fixturesPath.'/yaml/services_dump_load.yml', $dumper->dump());
     }
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/containers/container_uninitialized_ref.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/containers/container_uninitialized_ref.php
new file mode 100644
index 0000000000..9ecf7c909f
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/containers/container_uninitialized_ref.php
@@ -0,0 +1,46 @@
+<?php
+
+use Symfony\Component\DependencyInjection\Argument\IteratorArgument;
+use Symfony\Component\DependencyInjection\Argument\ServiceClosureArgument;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Reference;
+
+$container = new ContainerBuilder();
+
+$container
+    ->register('foo1', 'stdClass')
+;
+
+$container
+    ->register('foo2', 'stdClass')
+    ->setPublic(false)
+;
+
+$container
+    ->register('foo3', 'stdClass')
+    ->setPublic(false)
+;
+
+$container
+    ->register('baz', 'stdClass')
+    ->setProperty('foo3', new Reference('foo3'))
+;
+
+$container
+    ->register('bar', 'stdClass')
+    ->setProperty('foo1', new Reference('foo1', $container::IGNORE_ON_UNINITIALIZED_REFERENCE))
+    ->setProperty('foo2', new Reference('foo2', $container::IGNORE_ON_UNINITIALIZED_REFERENCE))
+    ->setProperty('foo3', new Reference('foo3', $container::IGNORE_ON_UNINITIALIZED_REFERENCE))
+    ->setProperty('closures', array(
+        new ServiceClosureArgument(new Reference('foo1', $container::IGNORE_ON_UNINITIALIZED_REFERENCE)),
+        new ServiceClosureArgument(new Reference('foo2', $container::IGNORE_ON_UNINITIALIZED_REFERENCE)),
+        new ServiceClosureArgument(new Reference('foo3', $container::IGNORE_ON_UNINITIALIZED_REFERENCE)),
+    ))
+    ->setProperty('iter', new IteratorArgument(array(
+        'foo1' => new Reference('foo1', $container::IGNORE_ON_UNINITIALIZED_REFERENCE),
+        'foo2' => new Reference('foo2', $container::IGNORE_ON_UNINITIALIZED_REFERENCE),
+        'foo3' => new Reference('foo3', $container::IGNORE_ON_UNINITIALIZED_REFERENCE),
+    )))
+;
+
+return $container;
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services_uninitialized_ref.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services_uninitialized_ref.php
new file mode 100644
index 0000000000..df0d74c07c
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services_uninitialized_ref.php
@@ -0,0 +1,138 @@
+<?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;
+
+/**
+ * Symfony_DI_PhpDumper_Test_Uninitialized_Reference.
+ *
+ * This class has been auto-generated
+ * by the Symfony Dependency Injection Component.
+ *
+ * @final since Symfony 3.3
+ */
+class Symfony_DI_PhpDumper_Test_Uninitialized_Reference extends Container
+{
+    private $parameters;
+    private $targetDirs = array();
+
+    /**
+     * Constructor.
+     */
+    public function __construct()
+    {
+        $this->services = array();
+        $this->methodMap = array(
+            'bar' => 'getBarService',
+            'baz' => 'getBazService',
+            'foo1' => 'getFoo1Service',
+            'foo3' => 'getFoo3Service',
+        );
+        $this->privates = array(
+            'foo3' => true,
+        );
+
+        $this->aliases = array();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function compile()
+    {
+        throw new LogicException('You cannot compile a dumped container that was already compiled.');
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function isCompiled()
+    {
+        return true;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    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 'bar' shared service.
+     *
+     * @return \stdClass
+     */
+    protected function getBarService()
+    {
+        $this->services['bar'] = $instance = new \stdClass();
+
+        $instance->foo1 = ${($_ = isset($this->services['foo1']) ? $this->services['foo1'] : null) && false ?: '_'};
+        $instance->foo2 = null;
+        $instance->foo3 = ${($_ = isset($this->services['foo3']) ? $this->services['foo3'] : null) && false ?: '_'};
+        $instance->closures = array(0 => function () {
+            return ${($_ = isset($this->services['foo1']) ? $this->services['foo1'] : null) && false ?: '_'};
+        }, 1 => function () {
+            return null;
+        }, 2 => function () {
+            return ${($_ = isset($this->services['foo3']) ? $this->services['foo3'] : null) && false ?: '_'};
+        });
+        $instance->iter = new RewindableGenerator(function () {
+            if (isset($this->services['foo1'])) {
+                yield 'foo1' => ${($_ = isset($this->services['foo1']) ? $this->services['foo1'] : null) && false ?: '_'};
+            }
+            if (false) {
+                yield 'foo2' => null;
+            }
+            if (isset($this->services['foo3'])) {
+                yield 'foo3' => ${($_ = isset($this->services['foo3']) ? $this->services['foo3'] : null) && false ?: '_'};
+            }
+        }, function () {
+            return 0 + (int) (isset($this->services['foo1'])) + (int) (false) + (int) (isset($this->services['foo3']));
+        });
+
+        return $instance;
+    }
+
+    /**
+     * Gets the public 'baz' shared service.
+     *
+     * @return \stdClass
+     */
+    protected function getBazService()
+    {
+        $this->services['baz'] = $instance = new \stdClass();
+
+        $instance->foo3 = ${($_ = isset($this->services['foo3']) ? $this->services['foo3'] : $this->getFoo3Service()) && false ?: '_'};
+
+        return $instance;
+    }
+
+    /**
+     * Gets the public 'foo1' shared service.
+     *
+     * @return \stdClass
+     */
+    protected function getFoo1Service()
+    {
+        return $this->services['foo1'] = new \stdClass();
+    }
+
+    /**
+     * Gets the private 'foo3' shared service.
+     *
+     * @return \stdClass
+     */
+    protected function getFoo3Service()
+    {
+        return $this->services['foo3'] = new \stdClass();
+    }
+}
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services_dump_load.xml b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services_dump_load.xml
new file mode 100644
index 0000000000..e763aa870a
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services_dump_load.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
+  <services>
+    <service id="service_container" class="Symfony\Component\DependencyInjection\ContainerInterface" synthetic="true"/>
+    <service id="foo" autoconfigure="true" abstract="true">
+      <argument type="service" id="bar" on-invalid="ignore_uninitialized"/>
+    </service>
+    <service id="Psr\Container\ContainerInterface" alias="service_container" public="false"/>
+    <service id="Symfony\Component\DependencyInjection\ContainerInterface" alias="service_container" public="false"/>
+  </services>
+</container>
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services_dump_load.yml b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services_dump_load.yml
index 43b0c7d58a..8f3e153afc 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services_dump_load.yml
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services_dump_load.yml
@@ -6,6 +6,7 @@ services:
     foo:
         autoconfigure: true
         abstract: true
+        arguments: ['@!bar']
     Psr\Container\ContainerInterface:
         alias: service_container
         public: false