Build vs fed AD as a support?

I know you pick up locket vs AP, crucible vs CC, but is there anything to buy to help them team vs a fed AD champ?

Last game for example, playing Morgana, against a very fed Zed, built my support item, boots, and locket. My top lane asked why I built locket. I always thought that locket was core for most support champs as it will always help.