It's worth nothing that CBP cannot compel you to give them your password(s), and can't really refuse entry to a US citizen, so as long as you encrypt everything your laptop should be secure. They can of course confiscate the machine to image it - and you may not get it back while it's still worth anything - but, what can you do.

The iPhone is trickier, mAdvLock is the only thing I know of that would most likely work even if it was confiscated.