This can be done by doing:
(lldb) platform select ios-simulator
(lldb) platform process list
There was code that was trying to detect simulator processes but it had an error in the loop where each time it would check for a env var that starts with "SIMULATOR_UDID=" it would change the architecture to iOS if it found it and MacOSX if it didn't. This meant unless "SIMULATOR_UDID=" was the last environment variable, this loop would never set the OS correctly. We also weren't setting the environment to Simulator which means PlatformAppleSimulator::FindProcesses(...) would never return any valid processes even when there were many.
I don't know how I can test this as we don't want a test suite having to launch an iOS simulator, so there are no tests at the moment. If anyone has any ideas on how to test this, please let me know.