diff --git a/scrapy/http/request/__init__.py b/scrapy/http/request/__init__.py
index 187238b1cb30df51ec288d5ab426ea49cdff70b2..4dce92880bc074539b85a23e915c3ca88624765e 100644
--- a/scrapy/http/request/__init__.py
+++ b/scrapy/http/request/__init__.py
@@ -96,20 +96,12 @@ class Request(object_ref):
         """Return a copy of this Request"""
         return self.replace()
 
-    def replace(self, url=None, callback=None, method=None, headers=None, body=None, \
-                cookies=None, meta=None, encoding=None, priority=None, \
-                dont_filter=None, errback=None):
+    def replace(self, *args, **kwargs):
         """Create a new Request with the same attributes except for those
         given new values.
         """
-        return self.__class__(url=self.url if url is None else url,
-                              callback=callback,
-                              method=self.method if method is None else method,
-                              headers=copy.deepcopy(self.headers) if headers is None else headers,
-                              body=self.body if body is None else body,
-                              cookies=self.cookies if cookies is None else cookies,
-                              meta=self.meta if meta is None else meta,
-                              encoding=self.encoding if encoding is None else encoding,
-                              priority=self.priority if priority is None else priority,
-                              dont_filter=self.dont_filter if dont_filter is None else dont_filter,
-                              errback=errback)
+        for x in ['url', 'method', 'headers', 'body', 'cookies', 'meta', \
+                'encoding', 'priority', 'dont_filter']:
+            kwargs.setdefault(x, getattr(self, x))
+        cls = kwargs.pop('cls', self.__class__)
+        return cls(*args, **kwargs)
diff --git a/scrapy/http/response/__init__.py b/scrapy/http/response/__init__.py
index f632ea117941140ea6a255897802b8422004731f..251e77ad777967be8c76059f21902e15a4becf60 100644
--- a/scrapy/http/response/__init__.py
+++ b/scrapy/http/response/__init__.py
@@ -71,18 +71,11 @@ class Response(object_ref):
         """Return a copy of this Response"""
         return self.replace()
 
-    def replace(self, url=None, status=None, headers=None, body=None, meta=None, \
-            flags=None, cls=None, **kwargs):
+    def replace(self, *args, **kwargs):
         """Create a new Response with the same attributes except for those
         given new values.
         """
-        if cls is None:
-            cls = self.__class__
-        new = cls(url=self.url if url is None else url,
-                  status=self.status if status is None else status,
-                  headers=copy.deepcopy(self.headers) if headers is None else headers,
-                  body=self.body if body is None else body,
-                  meta=self.meta if meta is None else meta,
-                  flags=self.flags if flags is None else flags,
-                  **kwargs)
-        return new
+        for x in ['url', 'status', 'headers', 'body', 'meta', 'flags']:
+            kwargs.setdefault(x, getattr(self, x))
+        cls = kwargs.pop('cls', self.__class__)
+        return cls(*args, **kwargs)