The world number two, who bounced back from a surprise early exit in Montreal by beating Mikhail Youzhny in Wednesday's second round, needed only an hour and 10 minutes to defeat 31-year-old Frenchman Benneteau 6-2 6-2.
The first set was a cruise for Scotland's Murray as three aces and a 75 per cent success rate on his return of serve put the former world number 15 firmly under the cosh.
Benneteau would show flashes of inspiration as the second set got under way but Murray - champion here in 2011 - was largely wise to his range of forehand shots and steadily ground down the Frenchman's resolve at the Lindner Family Tennis Center.
Murray's reward is a last-eight meeting with Tommy Robredo or fifth seed Tomas Berdych.
Defending champion Roger Federer survived what appeared to be another impending early tournament exit by raising his game to beat Tommy Haas.
The Swiss fifth seed has endured a difficult season, following up his only title win in Halle with a second-round defeat to Sergiy Stakhovsky at Wimbledon before slipping up in both Hamburg and on home soil at Gstaad.
After struggling with a larger prototype racket, the 32-year-old switched back to his favoured Wilson this week and the move paid dividends on Thursday night despite a quick 6-1 first-set raid from Germany's Haas.
Federer would struggle in the second set, too, but steadily found the edge he needed on his serve to close out a 1-6 7-5 6-3 win and earn a quarter-final meeting with either Grigor Dimitrov or world number three Rafael Nadal.
Also in the last eight is Novak Djokovic, who dispatched David Goffin 6-2 6-0 in just 51 minutes.
The Serbian world number one will play John Isner following the big-serving American's 7-5 (7/5) 6-4 triumph over Milos Raonic.
Elsewhere, seventh seed Juan Martin Del Potro dropped a set but closed out a 6-4 1-6 6-4 over Feliciano Lopez and his quarter-final opponent is Dmitry Tursunov.
The unseeded Russian produced a shock earlier in the afternoon by dismissing third seed David Ferrer of Spain in straight sets, 6-2 6-4.
There was no such giant-killing in the women's draw as second seed Victoria Azarenka sealed a comfortable 6-3 6-4 victory over Magdalena Rybarikova to set up a match against Caroline Wozniacki or Petra Kvitova.
Li Na remained in contention to defend her title by ousting Angelique Kerber 6-4 6-4 but fourth seed Agnieszka Radwanska showed her credentials with a one-sided 6-0 6-2 dismissal of Elena Vesnina.
Roberta Vinci beat her fellow Italian and doubles partner Sara Errani 6-4 6-3 to book a face-off with Jelena Jankovic, who was given a tough workout by home hopeful Sloane Stephens on her way to a 3-6 7-5 7-5 win.