AOL is putting the finishing touches on a high-tech system for mass-producing news articles, entertainment and other online content, the linchpin of Chief Executive Tim Armstrong’s strategy for reviving the struggling 25-year-old Internet company after Time Warner spins it off next month. Mr. Armstrong’s goal is to make AOL, which has been losing visitors and revenue, a magnet for both advertisers and consumers by turning it into the top creator of digital content. He hopes to do so in part by turning some media and marketing conventions on their ear, and potentially blurring the lines between journalism and advertising. AOL is betting it can reinvent itself with a numbers-driven approach to developing content, based on what Web-search and other data tell it is most likely to attract audiences and sponsors. Instead of waiting to sell ads until an article or Web video is produced, AOL—which has scores of niche sites, such as beauty and fashion site Stylelist, in addition to its AOL brand—says it plans to offer marketers the chance to work with its editorial team to create custom content. AOL says that its ad model will allow advertisers to be affiliated with the content but not control what is written or created. Media experts and others say that disclosing when articles or videos have been shaped by advertisers will be crucial to AOL’s credibility.