$List = $spWeb.Lists[$docLibName]
$docFile = $List.get_Items() | ?{$_.Name -EQ $docName}
Add-content $DownloadFieldFile -value $docFile.Xml

[Microsoft.SharePoint.SPFile]$spFile = $List.RootFolder.Files.Add($List.RootFolder.URL + "/" + $newDocFile.Name, [System.IO.Stream]$fileStream, $true)