toString override in C++

In Java, when a class overrides .toString() and you do System.out.println() it will use that.

class MyObj {
    public String toString() { return "Hi"; }
}
...
x = new MyObj();
System.out.println(x); // prints Hi

How can I accomplish that in C++, so that:

Object x = new Object();
std::cout << *x << endl;

Will output some meaningful string representation I chose for Object?