There is nothing built in, but it's straightforward with combinable (a reduction variable) and a parallel loop (here parallel_for_each). However if the work you are doing is only 'max' of numbers unless the amount of numbers you are looking at is very large, it may be difficult to see speedups.
You can read more about it on msdn:
#include <ppl.h>
#include <climits>
#include <vector>
#include <numeric>
#include <iostream>
using namespace Concurrency;
int main(int argc, _TCHAR* argv[])
{
std::vector<int> vec(10);
std::iota( begin(vec), end(vec), 1);
combinable<int> locals([]{ return INT_MIN; });
parallel_for_each( begin(vec), end(vec), [&locals](int cur){
auto & localMax = locals.local();
localMax = std::max(cur, localMax);
});
std::cout << "max is " << locals.combine([](int left, int right){ return std::max<int>(left, right);}) << std::endl;
return 0;
}