Please see this guide if you run into trouble auto-patching LA Noire on Windows 7:
• Turn off "Realtime Protection" on Your firewall and Anti-Virus a moment
• Install the game to "C:\Program Files\RockstarGames\L.A.Noire" instead of the default path.
• After opening the game, it will begin to patch. It may get stuck, you may need to cancel.
• After closing the game, remove all .patched files, then right clicked on the patch exe and "Opened As Administrator." It then will install.
• Open the game, it may make you restart the game again.
If you continue to experience issues with the game's auto patcher we will have to defer to the experts at Rockstar Games.
For Windows 8, there is a manual Patch available here: http://support.rockstargames.com/entries/22390066-11-14-12-l-a-noire-patch-notes-and-manual-links-to-updates
Your game activation and technical support is provided by Rockstar Games. Please go to http://support.rockstargames.com/home