This is one of the well-sought features, and IPS are used in conjunction with a feature called virtual patching, which is quite interesting.
Let's assume that there is a vulnerability present in a public web server that is still not patched. In a generic approach, an attacker can easily fire an exploit and send the payload to the server. However, as a part of virtual patching, the IPS will block the exploit even though the vulnerability is present on the server.
This is especially useful in many cases, where upgrading software might not be possible due to business reasons.
