How to update all the VCS packages at the same time?

[郑文辉(Techlive Zheng) <techlivezheng@xxxxxxxxx>]

I have installed several VCS packages from AUR which the PKGBUILD has
not been updated for a while, is there a way to force update them all
together? By the way, I use yaourt, but I don't know if there is a
option can do that.

Thanks