Netflix's lead in internet video streaming is unstoppable, according to one Wall Street firm.

Macquarie Research raised its rating for Netflix shares to outperform from neutral, citing the success of the company's original-content strategy.

"Netflix is miles ahead in terms of programming hours, original content quality and time spent, and we don't expect this to change. Netflix has won," analyst Tim Nollen wrote in a note to clients Tuesday.

Netflix shares were up 1.5 percent in Tuesday's premarket session. The company's stock rose 55 percent in 2017 versus the S&P 500's 19 percent return.

Nollen predicts Netflix will increase its percentage of original content to 60 percent in 2020 from an estimated 25 percent in 2017, resulting in a $2 billion cost savings in licensing fees.

"Netflix is expanding its distribution relationships with cable operators and telcos globally, international growth is taking off on a concerted strategy to develop local content offerings, and Netflix is beginning to work on ways to reduce password sharing, which could drive even more subs," he wrote.

Nollen increased his price target for Netflix shares to $220 from $200, representing 15 percent upside to Friday's close.

"Netflix has changed the way people watch TV, and is now pushing further into film. Consumers' increasing lack of tolerance for advertising drives them to subscription OTT services," the analyst wrote. "Disney's eventual OTT service is still two years away, and won't threaten Netflix, which besides holding onto a strong US sub base is establishing passion brand status in many international markets."