It'll be marriage No. 3 for the "Inherent Vice" actor, 47, who according to an Us Weekly source proposed to his former personal assistant last month.
"I'm in a totally different space," Brolin declared to USA Today in January 2014. "I'm the happiest I've ever been, other than having my kids. I wake up in the morning and I'm actually happy."
The next month, he and Boyd were photographed getting romantic in Rome, and they were recently spotted celebrating something with friends in Cabo San Lucas, according to an eyewitness who spoke to People and Us Weekly.
"They were kissing each other a lot, had their arms around each other," the source told Us. "Super affectionate all night."
Brolin's first wife was actress Alison Adair. They have two adult children together. The "No Country for Old Men" actor was also previously engaged to Minnie Driver, but they called it quits before walking down the aisle.