The world number 12 lost control in the second set after his opponent broke in the fourth game.
In the deciding tiebreak, Simon could not handle Llodra's attacking game and bowed out with a long volley.
Simon, who has now lost all four meeting against Llodra, will have a final chance of securing a place in the season-ending tournament in London when he competes at the Paris Masters next month.
Llodra will face Ivan Ljubicic in Sunday's final after the Croatian dismissed French wildcard Arnaud Clement 6-2 6-4.
(Reporting by Eric Salliot, writing by Julien Pretot in Paris; editing by Pritha Sarkar; To query or comment on this story email sportsfeedback@thomsonreuters.com)
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