diff --git a/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php b/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php
index 94ed6d8b63..88732bbd3e 100644
--- a/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php
+++ b/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php
@@ -32,6 +32,8 @@ class ObjectNormalizer extends AbstractObjectNormalizer
 
     private $discriminatorCache = [];
 
+    private $objectClassResolver;
+
     public function __construct(ClassMetadataFactoryInterface $classMetadataFactory = null, NameConverterInterface $nameConverter = null, PropertyAccessorInterface $propertyAccessor = null, PropertyTypeExtractorInterface $propertyTypeExtractor = null, ClassDiscriminatorResolverInterface $classDiscriminatorResolver = null, callable $objectClassResolver = null, array $defaultContext = [])
     {
         if (!\class_exists(PropertyAccess::class)) {
@@ -41,6 +43,7 @@ class ObjectNormalizer extends AbstractObjectNormalizer
         parent::__construct($classMetadataFactory, $nameConverter, $propertyTypeExtractor, $classDiscriminatorResolver, $objectClassResolver, $defaultContext);
 
         $this->propertyAccessor = $propertyAccessor ?: PropertyAccess::createPropertyAccessor();
+        $this->objectClassResolver = $objectClassResolver;
     }
 
     /**
@@ -60,7 +63,9 @@ class ObjectNormalizer extends AbstractObjectNormalizer
         $attributes = [];
 
         // methods
-        $reflClass = new \ReflectionClass($object);
+        $class = $this->objectClassResolver ? ($this->objectClassResolver)($object) : \get_class($object);
+        $reflClass = new \ReflectionClass($class);
+
         foreach ($reflClass->getMethods(\ReflectionMethod::IS_PUBLIC) as $reflMethod) {
             if (
                 0 !== $reflMethod->getNumberOfRequiredParameters() ||
diff --git a/src/Symfony/Component/Serializer/Tests/Normalizer/ObjectNormalizerTest.php b/src/Symfony/Component/Serializer/Tests/Normalizer/ObjectNormalizerTest.php
index b2bc76a86a..b4e0805281 100644
--- a/src/Symfony/Component/Serializer/Tests/Normalizer/ObjectNormalizerTest.php
+++ b/src/Symfony/Component/Serializer/Tests/Normalizer/ObjectNormalizerTest.php
@@ -1003,6 +1003,34 @@ class ObjectNormalizerTest extends TestCase
         $normalizer = new ObjectNormalizer(null, $nameConverter);
         $this->assertArrayHasKey('foo-Symfony\Component\Serializer\Tests\Normalizer\ObjectDummy-json-bar', $normalizer->normalize(new ObjectDummy(), 'json', ['foo' => 'bar']));
     }
+
+    public function testObjectClassResolver()
+    {
+        $classResolver = function ($object) {
+            return ObjectDummy::class;
+        };
+
+        $normalizer = new ObjectNormalizer(null, null, null, null, null, $classResolver);
+
+        $obj = new ProxyObjectDummy();
+        $obj->setFoo('foo');
+        $obj->bar = 'bar';
+        $obj->setBaz(true);
+        $obj->setCamelCase('camelcase');
+        $obj->unwantedProperty = 'notwanted';
+
+        $this->assertEquals(
+            [
+                'foo' => 'foo',
+                'bar' => 'bar',
+                'baz' => true,
+                'fooBar' => 'foobar',
+                'camelCase' => 'camelcase',
+                'object' => null,
+            ],
+            $normalizer->normalize($obj, 'any')
+        );
+    }
 }
 
 class ObjectDummy
@@ -1064,6 +1092,11 @@ class ObjectDummy
     }
 }
 
+class ProxyObjectDummy extends ObjectDummy
+{
+    public $unwantedProperty;
+}
+
 class ObjectConstructorDummy
 {
     protected $foo;