Note: This is a mod made by a user named Fatalis. I am only reposting it here so more people can download it

Here is the original readme:

Deus Ex: Human Revolution - noclip Mod by Fatalis
v1.1

This mod unlocks noclip in DXHR and DXHR Director's Cut. It requires you to use an
Xbox 360 controller because the developers made it that way. If it crashes or if
the game gets an update that breaks the mod, contact me: [email protected].
This will only work on the latest Steam versions of the game.

Instructions:

Extract fmodex.dll and dxhr_noclip.dll files in the appropriate folder to your DXHR or
DXHR DC steam folder. Example:
"C:\Program Files (x86)\Steam\SteamApps\common\Deus Ex - Human Revolution"

You may want to back up your fmodex.dll file before doing this. If you need to remove
the mod later and you overwrote this file, just use Steam's 'Verify Integrity of Game
Cache' feature in the game's properties.

Open the game. If the mod loaded successfully, the version number on the main menu
should say "noclipmod".

Once in-game, press F3 or both of the Xbox 360 stick buttons (L3/R3) simultaneously.
You can exit noclip the same way. RB/LB change the speed and Dpad Up/Down move you up
and down.

Technical Information:

See the 'src' folder for the source code. It's not pretty.

fmodex.dll's import table is modified to load dxhr_noclip.dll

The game has a few debug camera modes left in. The code basically unlocks the use of
'FreeCamera' and simulates noclip by teleporting the player when leaving freecam mode.