Swiss driver Neel Jani, in the number 18 Porsche 919 hybrid car shared with France's Romain Dumas and Germany's Marc Lieb, took the pole position for Saturday's start with a best lap of three minutes 16.887 seconds set on Wednesday.
Australian Mark Webber, in the number 17 car, was second fastest while Force India F1 driver Nico Hulkenberg will line up third in the number 19.
Champions Audi qualified fourth, fifth and sixth with the number seven car of last year's winners Andre Lotterer, Benoit Treluyer and Marcel Fassler fifth. Toyota was seventh and eighth.
Porsche, which returned to Le Mans with a works team in 2014 for the first time in 16 years, is the most successful manufacturer with 16 titles.
Audi, which has won the race 13 times and are part of the Volkswagen Group with Porsche, are expected to challenge strongly during the race even if their rivals are quicker over a single lap.
Danish veteran Jan Magnussen, father of McLaren Formula One reserve Kevin, crashed his Corvette heavily in Thursday's second session.
Magnussen was conscious and talking after the accident and taken to the circuit medical centre before being discharged.
Original source: Porsche dominates Le Mans start grid