Is there a way, either in code or with JVM arguments, to override the current time, as presented via System.currentTimeMillis, other than manually changing the system clock on the host machine?

A little background:

We have a system that runs a number of accounting jobs that revolve much of their logic around the current date (ie 1st of the month, 1st of the year, etc)

Unfortunately, a lot of the legacy code calls functions such as new Date() or Calendar.getInstance(), both of which eventually call down to System.currentTimeMillis.

For testing purposes, right now, we are stuck with manually updating the system clock to manipulate what time and date the code thinks that the test is being run.

So my question is:

Is there a way to override what is returned by System.currentTimeMillis? For example, to tell the JVM to automatically add or subtract some offset before returning from that method?

Thanks in advance!