In a major boost to the suburban Boston real estate market, Quest Diagnostics Inc. is planning to open a new laboratory complex in Marlborough that will bring nearly 1,200 jobs to the city over the next few years, officials said Thursday.

The New Jersey-based provider of medical testing services said it will spend more than $64 million to renovate a portion of the former Hewlett-Packard Co. complex on Forest Street. Quest has signed a letter of intent to lease 200,000 square feet for a laboratory and administrative facility to support its Northeast operations.