Wedding wear

We've been invited to a friend's wedding in August and I'm already busy planning what to wear ... and not just for myself.
While I'm eyeing off gorgeous wintry frocks and mentally teaming them with Mary Jane heels and chunky necklaces, I've also had to think about what Ari will wear.
I have reservations about kids at weddings - we didn't invite children to our own wedding. But Ari's name came on the invite, so he's going ... as long as he doesn't drink too much!
But what do babies wear to weddings?
If he was an older toddler, I'd be thinking about a little suit or at least a neat little shirt and trousers.
But a 5 month old baby? His usual ensemble of stripey Bonds jumpsuit and jacket/cardigan just doesn't seem dressy enough.
After scouring the Internet, it appears that (as usual) there's not much around. And of course, what I did find was just hilariously awful (see pictured).
I would love to be able to dress Ari in a little shirt with a skinny rockstar tie a la Interpol or Franz Ferdinand (see pictured), but I think I'm aiming waaay too high.