Retrospectively timing long-running operations in PowerShell

Sometimes I run an operation that takes longer than I expect to execute, but once it is finished, the only way to see how long it did take is to run it again in Measure-Command or use some other timing mechanism. This PowerShell prompt preserves your existing prompt (for example PoshGit) and tacks on an execution time for each and every command you run.

C:\Demo [master]> Start-Sleep 3
00:00:03.0048920
C:\Demo [master]> Start-Sleep 5
00:00:04.9974939
C:\Demo [master]>
00:00:00.0004274
C:\Demo [master]>