Atomic Minimum on x86 using OpenMP

Does OpenMP support an atomic minimum for C++11? If OpenMP has no portable method: Is there some way of doing it using a x86 or amd64 feature?

In the OpenMP specifications I found nothing for C++ but the Fortran version seems to support it. See 2.8.5 of the v3.1 for the details. For C++ it states

binop is one of +, *, -, /, &, ^, |, <<, or >>.

but for Fortran it states

intrinsic_procedure_name is one of MAX, MIN, IAND, IOR, or IEOR.

In case you are interested in more context: I am looking for a mutex free method of doing the following:

vector<omp_lock_t>lock;
vector<int>val;

#pragma omp parallel
{
  // ...
  int x = ...;
  int y = ...;
  if(y < val[x]){
    omp_set_lock(&lock[x]);
    if(y < val[x])
      val[x] = y;
    omp_unset_lock(&lock[x]);
  }
}

I know that you can compute the minimum using a reduce algorithm. I know that there are circumstances where this largely outperforms any atomic minimum approach. However, I also know that this is not the case in my situation.

EDIT: One option that is slightly faster in my case is

  int x = ...;
  int y = ...;
  while(y < val[x])
    val[x] = y;

but that is no atomic operation.

All the newer GPUs have this feature and I am missing it on the CPU. (See atom_min for OpenCL.)