Bit.ly is a legitimate URL shortening service. However, it is also abused by malicious actors to hide the final destination URL. When you see bit.ly in a suspicious keyword, it strongly suggests that the author is trying to prevent security software from analyzing the link. A typical malicious use would be:

The string is likely a fragmented, low-quality search for a Windows 8.1 crack or keygen. Following such links is one of the fastest ways to infect your computer.