At my last job, several employees openly supported Trump, and they didn't suffer any consequences.
EDIT: Jokes aside, I simply do not talk about political affiliations with anyone, whatsoever. I have no problem having a little back and forth regarding an issue here or an issue there as well as discussing heavier subjects such as foreign policy. To be honest, I do find myself policing my language to not give away who I may or may not have voted for in the past every now and then.
I should probably note I live outside of the US and talking politics can really mess with everyday relationships. I made a decision to vote only on issues while trying to abstain from the whole "this is my sports team" mentality which sort of takes hold of people where I live.
It's interesting that you specifically choose "libertarian". While maybe technically further to the right than Republican it truly seems supporting specifically Republican candidates is wholly furiously unacceptable in the bay area -- especially at tech companies. Try wearing a pin, t-shirt, hat, etc... "openly" supporting Trump to a tech company in the city -- actually for the safety of your career and physical self better not.