When my international flight landed at LAX today, I saw a sign to download a mobile app to expedite the process of getting through U.S. Customs. I quickly downloaded it. It was very easy to scan my passport to import the information, to answer the CBP inspection-related questions, and to snap a selfie.
After that, I proceeded to where everyone was waiting in line for the automated machines. I told someone that worked there that I was using the mobile app, and she directed me to station 51 which had no line whatsoever! I breezed through customs in like 5 minutes!
Here is more information on the CBP website and the Mobile Passport - Officially Authorized by CBP app in the Apple AppStore.
I recommend getting this on your phone and setting up your passport before arriving at the airport to save even more time. When you land, before you even exit the plane, you'll just have to "create a trip", answer the trip-specific questions, and you'll be on your way.