Is there a short phrase that expresses sincere thankfulness to someone who takes time to help me?

When I want to express my thankfulness to someone who takes time to help me, I would say:

您辛苦了

in Chinese, or

お疲れ様でした

in Japanese.

Imprecisely, this means:

You have taken a lot of time and might even have suffered some pain in fulfilling a certain thing (which is related to me, or even completely for me). So, you must be tired afterward. (Please accept my sincere thanks.)

Is there any short phrase in English expressing this meaning?

Google gave me a translation of "您辛苦了" to English, which is:

You have worked hard.

But I don't think this is proper, because to my understanding, this sentence is more a judgment than a way of showing gratitude.

I think there might be no similar expression in English, because of cultural differences. But please tell me if there is any.

Solution 1:

I don't know Chinese, but a translation of お疲れ様でした (otsukaresama deshita) into casual English would be something like:

Thanks for taking the trouble.

Thanks for your trouble.

Sorry to trouble you.

Sorry to bother you.

Sorry to put you out.

Etc.

Or even something as simple as:

Many thanks.

Thanks a lot. I appreciate it.

Solution 2:

One could say:

Thank you for your pains!
Do not trouble yourself too much

Solution 3:

I don't want this to seem pedantic, but I took a tech writing course in college where the prof hated this expression if you used it before you asked for help... He found it incredibly presumptuous... He thought it rude to basically assume that the person you asked for help actually will help you... So to that:

My old prof would say: "I would appreciate your help"

But if you're not in a sensitive situation then "Thanks for your help" or "Thank you for taking the trouble" (@Robusto) would work great.