diff -r f9dd607dc04c Objects/abstract.c
--- a/Objects/abstract.c	Tue Jan 03 02:01:42 2017 +0100
+++ b/Objects/abstract.c	Tue Jan 03 02:37:43 2017 +0100
@@ -2700,58 +2700,72 @@ PyObject *
     return retval;
 }
 
-PyObject *
-_PyObject_VaCallFunctionObjArgs(PyObject *callable, va_list vargs)
+static PyObject *
+object_vacall(PyObject *callable, va_list vargs)
 {
-    PyObject *small_stack[_PY_FASTCALL_SMALL_STACK];
+    Py_ssize_t allocated, nargs;
     PyObject **stack;
-    Py_ssize_t nargs;
     PyObject *result;
-    Py_ssize_t i;
-    va_list countva;
 
     if (callable == NULL) {
         return null_error();
     }
 
-    /* Count the number of arguments */
-    va_copy(countva, vargs);
     nargs = 0;
+    allocated = 0;
+    stack = NULL;
     while (1) {
-        PyObject *arg = va_arg(countva, PyObject *);
+        PyObject *arg = va_arg(vargs, PyObject *);
         if (arg == NULL) {
             break;
         }
         nargs++;
-    }
-    va_end(countva);
-
-    /* Copy arguments */
-    if (nargs <= (Py_ssize_t)Py_ARRAY_LENGTH(small_stack)) {
-        stack = small_stack;
-    }
-    else {
-        stack = PyMem_Malloc(nargs * sizeof(stack[0]));
-        if (stack == NULL) {
-            PyErr_NoMemory();
-            return NULL;
+
+        if (nargs > allocated) {
+            if (stack == NULL) {
+                /* Size chosen to be small enough to not waste heap memory
+                   and to reduce the need of realloc() */
+                allocated = 8;
+
+                stack = PyMem_Malloc(allocated * sizeof(PyObject*));
+                if (stack == NULL) {
+                    PyErr_NoMemory();
+                    return NULL;
+                }
+            }
+            else {
+                PyObject **stack2;
+
+                /* overallocate to reduce the number of realloc() */
+                allocated = nargs * 2;
+
+                stack2 = PyMem_Realloc(stack, allocated * sizeof(PyObject*));
+                if (stack2 == NULL) {
+                    PyMem_Free(stack);
+                    PyErr_NoMemory();
+                    return NULL;
+                }
+                stack = stack2;
+            }
         }
-    }
-
-    for (i = 0; i < nargs; ++i) {
-        stack[i] = va_arg(vargs, PyObject *);
+        stack[nargs - 1] = arg;
     }
 
-    /* Call the function */
     result = _PyObject_FastCall(callable, stack, nargs);
 
-    if (stack != small_stack) {
-        PyMem_Free(stack);
-    }
+    /* Note: stack is NULL if nargs is equal to 0, which is fine */
+    PyMem_Free(stack);
+
     return result;
 }
 
 PyObject *
+_PyObject_VaCallFunctionObjArgs(PyObject *callable, va_list vargs)
+{
+    return object_vacall(callable, vargs);
+}
+
+PyObject *
 PyObject_CallMethodObjArgs(PyObject *callable, PyObject *name, ...)
 {
     va_list vargs;
@@ -2767,7 +2781,7 @@ PyObject_CallMethodObjArgs(PyObject *cal
     }
 
     va_start(vargs, name);
-    result = _PyObject_VaCallFunctionObjArgs(callable, vargs);
+    result = object_vacall(callable, vargs);
     va_end(vargs);
 
     Py_DECREF(callable);
@@ -2791,7 +2805,7 @@ PyObject *
     }
 
     va_start(vargs, name);
-    result = _PyObject_VaCallFunctionObjArgs(callable, vargs);
+    result = object_vacall(callable, vargs);
     va_end(vargs);
 
     Py_DECREF(callable);
@@ -2805,7 +2819,7 @@ PyObject_CallFunctionObjArgs(PyObject *c
     PyObject *result;
 
     va_start(vargs, callable);
-    result = _PyObject_VaCallFunctionObjArgs(callable, vargs);
+    result = object_vacall(callable, vargs);
     va_end(vargs);
 
     return result;