Justin Bieber Flashes Abs After Hiking Excursion in Hollywood Hills

Justin Bieber hit up a Los Angeles hiking trail over Labor Day weekend, taking the opportunity to strip down and flaunt his flat abs.

The "Sorry" singer was clearly feeling the heat of the California sun during the hike in the Hollywood Hills. He peeled off his shirt to rep his Calvin Klein undies and rock his six-pack au natural.

While rumored girlfriend Sofia Richie wasn't with Bieber this time, she wasn't far away. The 18-year-old model posted an Instagram snapshot also from an LA-area hiking trail on Saturday. 

Bieber whisked Richie away to Mexico late last month to celebrate her 18th birthday. While the singer recently shut down his Instagram, Richie happily chronicled the getaway on her social media channels.