Hostess Brands Inc. is preparing to file for Chapter 11 bankruptcy protection as soon as this week, said people familiar with the matter, a move that would mark the second significant court restructuring for the Twinkies and Wonder Bread baker in the past several years.

The privately held Irving, Texas, company, which employs roughly 19,000 people and carries more than $860 million in debt, has been facing a cash squeeze amid high labor costs and rising prices for sugar, flour and other ingredients, according to people familiar...