Born in Saint-Basile, Louis was the son of Joseph Cyr and Émélie Martin. Louis went through elementary school at the Academy of Hôtel-Dieu from 1903 to 1910, then did his classical studies at College of Sainte-Anne-de-la-Pocatière. His theological studies finished at Holy Heart Seminary in Halifax, Louis was ordained priest at Saint-Basile in 1922. After having been the parish priest in Saint-Joseph for fifteen years, he went to Saint-Jacques, where he remained until 1961, the year he retired. Genealogy was then his preferred hobby.