Lalo is the first Puerto Rican to win the prize.
Set in the streets, taverns and other darker sides of San Juan, a city normally associated with the sun and surf of the Caribbean, his book is about a novelist who starts receiving anonymous messages in the form of quotes from famous writers.
These lead him to a series of meetings, the last of which changes his life. Woven into the labyrinth is a tortured love story.
The prize includes a 100,000 dollar stipend. Lalo will take delivery of the prize in August.
Previous winners include Colombia's Gabriel Garcia Marquez, Mario Vargas Llosa of Peru and Carlos Fuentes of Mexico.