$HyperVHost = "MyHyperV"
filter Import-CimXml
{
   $CimXml = [Xml]$_
   $CimObj = New-Object -TypeName System.Object
   foreach ($CimProperty in $CimXml.SelectNodes("/INSTANCE/PROPERTY"))
   {
       $CimObj | Add-Member -MemberType NoteProperty -Name $CimProperty.NAME -Value $CimProperty.VALUE
   }
   $CimObj
}
 
$VMs = Get-VM -ComputerName $HyperVHost
foreach ($VM in $VMs)
{
   $VMInfo = Get-WmiObject -ComputerName $HyperVHost -Namespace root\virtualization -Query "Select * From Msvm_ComputerSystem Where ElementName='$VM'"
   $KVPData = Get-WmiObject -ComputerName $HyperVHost -Namespace root\virtualization -Query "Associators of {$VMInfo} Where AssocClass=Msvm_SystemDevice ResultClass=Msvm_KvpExchangeComponent"
   $KVPExport = $KVPData.GuestIntrinsicExchangeItems
   $Hostname = ($KVPExport | where {$_.Name -eq "FullyQualifiedDomainName"}).Data
   $VM | Rename-VM -NewName $Hostname
}