diff --git a/lib/connector/sabre/auth.php b/lib/connector/sabre/auth.php
index 6990d928cffee9d462e08cb8d2c6de2c615fc571..bf3a49593cbc23419ed2dd404f589bb5b1dd24e8 100644
--- a/lib/connector/sabre/auth.php
+++ b/lib/connector/sabre/auth.php
@@ -60,4 +60,25 @@ class OC_Connector_Sabre_Auth extends Sabre_DAV_Auth_Backend_AbstractBasic {
 		}
 		return $user;
 	}
+
+	/**
+	  * Override function here. We want to cache authentication cookies
+	  * in the syncing client to avoid HTTP-401 roundtrips.
+	  * If the sync client supplies the cookies, then OC_User::isLoggedIn()
+	  * will return true and we can see this WebDAV request as already authenticated,
+	  * even if there are no HTTP Basic Auth headers.
+	  * In other case, just fallback to the parent implementation.
+	  *
+	  * @return bool
+	  */
+	public function authenticate(Sabre_DAV_Server $server, $realm) {
+		if (OC_User::isLoggedIn()) {
+			$user = OC_User::getUser();
+			OC_Util::setupFS($user);
+			$this->currentUser = $user;
+			return true;
+		}
+
+		return parent::authenticate($server, $realm);
+    }
 }