Hopes were high that Doyle would register her first Group One success and Dame Malliot gave everything, only to be run out of it in the closing stages.
The Ed Vaughan-trained filly made the running and held every chance well into the final furlong, sticking on well when headed.
Donjah came with a telling run in the centre of the course to hit the front deep inside the final furlong, with Kaspar just holding Dame Malliot for second place.
Barney Roy, the other British raider for trainer Charlie Appleby and jockey William Buick, was fourth.
Doyle said: “It was a massive run. We were really pleased with her effort.
“There was no pace on and she relaxed really well. I got an easy enough lead and she responded well.
"She didn't handle the two turns great, but it was a game effort.”
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