I don't think the polls lied (lied implies intent). I think a few things happened. Pollsters have a really hard time getting hold of Trump voters for a few reasons: folks are scared to admit they voted for Trump, and those who are proud Trump supporters have such disdain for the media (of which pollsters are a part) that they simply hang up / don't engage.

So, Trump tends to get underrepresented in the polls.

At any rate, the polls showed that there was a dead heat, so this really came down to the margin of error which has historically somewhat favored Trump.