Jose Callejon, Alvaro Morata and Jese added to the Argentine duo's strikes in an impressive outing for Jose Mourinho's men, though their performance tailed off after the break
Madrid took the lead through Gonzalo Higuain inside two minutes before his compatriot Angel Di Maria made it two. David Lopes pulled one back for Galaxy but Jose Mourinho's men soon bucked up their ideas and added another goal through Jose Callejon before Alvaro Morata and Jese Rodriguez struck in the second half.
The Blancos did not begin the game with Cristiano Ronaldo on the pitch yet they lacked no potency in attack as they took the lead within 90 seconds. Di Maria drifted in from the right flank and threaded a perfectly-weighted through ball to Higuain and he slotted the ball past Josh Saunders.
The early onslaught continued as Madrid ripped through the hosts' left side and in the 11th minute their lead was doubled. Di Maria picked up the ball to the right of the box and cut inside onto his left foot before unleashing a powerful low shot that beat the keeper at his near post.
He continued to toy with the Galaxy defence and there should well have been a third moments later when the Argentine charged to the byeline but no one was on hand to tap in his squared pass.
The California outfit soon began to find their feet however, and after efforts from Bryan Gaul and Robbie Keane failed to hit the target, they pulled a goal back in the 23rd minute. David Beckham's expert free-kick delivery was headed across goal by Omar Gonzalez and Lopes bundled it over the line.
That shock seemed to spur Madrid back into life and they restored their two-goal advantage with a trademark counterattack. At the end of a swift break Higuain spotted the diagonal run of Callejon and slid the ball into the path of the 25-year-old who found the far corner nine minutes before the break.
There were more opportunities for both teams to find the net before the break but Keane had an effort saved by Iker Casillas before Higuain rounded Saunders but saw his attempt blocked by a covering defender.
Wholesale changes were made for both teams at half time, which included the introduction of Ronaldo, but it did not alter the momentum of the game. In the 49th minute Esteban Granero clipped a pass into the area which Morata controlled before casually placing past Brian Perk.
The intensity of the game died down after the goal and the Blancos lacked the fluidity and conviction in attack that they showed with Higuain and Di Maria on the pitch.
Some excellent saves from Perk in the closing stages almost kept some level of respectability to the score but with six minutes of normal time remaining Jese added the finishing touch to Mesut Ozil's cross, nestling the ball in the bottom corner.
Ronaldo was unlucky not to get on the scoresheet in the final moments as Tommy Meyer denied the Portuguese with a goal-line clearance.
The Spanish champions continue their pre-season preperations with a friendly against Juventus while Galaxy turn their attentions back to the MLS with an important fixture versus Seattle Sounders.