diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 5bde6870717c90..83380ada67838c 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -43,6 +43,20 @@ always available.
       functions will not see the hook.
 
 
+.. function:: addpendingcall(callback)
+
+   Schedule a *callback* to eventually execute in the main thread.
+
+   A :exc:`RuntimeError` is raised if the *callback* could not be
+   scheduled.
+
+   If *callback* raises an exception it is converted into an
+   *unraisable exception*, see :func:`sys.unraisablehook` for more
+   details.
+
+   .. versionadded:: 3.8
+
+
 .. data:: argv
 
    The list of command line arguments passed to a Python script. ``argv[0]`` is the
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-05-29-18-47-09.bpo-37088.ZsTtci.rst b/Misc/NEWS.d/next/Core and Builtins/2019-05-29-18-47-09.bpo-37088.ZsTtci.rst
new file mode 100644
index 00000000000000..2542ef76ff80de
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-05-29-18-47-09.bpo-37088.ZsTtci.rst	
@@ -0,0 +1 @@
+Add the sys.addpendingcall() function.
diff --git a/Python/clinic/sysmodule.c.h b/Python/clinic/sysmodule.c.h
index 6f248ff18d9d7f..372352d752797e 100644
--- a/Python/clinic/sysmodule.c.h
+++ b/Python/clinic/sysmodule.c.h
@@ -1051,6 +1051,38 @@ sys_getandroidapilevel(PyObject *module, PyObject *Py_UNUSED(ignored))
 
 #endif /* defined(ANDROID_API_LEVEL) */
 
+PyDoc_STRVAR(sys_addpendingcall__doc__,
+"addpendingcall($module, /, callback)\n"
+"--\n"
+"\n"
+"Schedule a *callback* to eventually execute in the main thread.");
+
+#define SYS_ADDPENDINGCALL_METHODDEF    \
+    {"addpendingcall", (PyCFunction)(void(*)(void))sys_addpendingcall, METH_FASTCALL|METH_KEYWORDS, sys_addpendingcall__doc__},
+
+static PyObject *
+sys_addpendingcall_impl(PyObject *module, PyObject *callback);
+
+static PyObject *
+sys_addpendingcall(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+{
+    PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"callback", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "addpendingcall", 0};
+    PyObject *argsbuf[1];
+    PyObject *callback;
+
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 1, 1, 0, argsbuf);
+    if (!args) {
+        goto exit;
+    }
+    callback = args[0];
+    return_value = sys_addpendingcall_impl(module, callback);
+
+exit:
+    return return_value;
+}
+
 #ifndef SYS_GETWINDOWSVERSION_METHODDEF
     #define SYS_GETWINDOWSVERSION_METHODDEF
 #endif /* !defined(SYS_GETWINDOWSVERSION_METHODDEF) */
@@ -1082,4 +1114,4 @@ sys_getandroidapilevel(PyObject *module, PyObject *Py_UNUSED(ignored))
 #ifndef SYS_GETANDROIDAPILEVEL_METHODDEF
     #define SYS_GETANDROIDAPILEVEL_METHODDEF
 #endif /* !defined(SYS_GETANDROIDAPILEVEL_METHODDEF) */
-/*[clinic end generated code: output=43c4fde7b5783d8d input=a9049054013a1b77]*/
+/*[clinic end generated code: output=d09a9c68a5603785 input=a9049054013a1b77]*/
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 343601ec8596f1..7d975f593327ae 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1895,6 +1895,44 @@ sys_getandroidapilevel_impl(PyObject *module)
 #endif   /* ANDROID_API_LEVEL */
 
 
+static int
+_call_pending_pycallback(void *arg)
+{
+    PyObject *callback = (PyObject *)arg;
+    PyObject *res = PyObject_CallFunctionObjArgs(callback, NULL);
+
+    if (res == NULL) {
+        PyErr_WriteUnraisable(callback);
+    }
+    else {
+        Py_DECREF(res);
+    }
+
+    return 0;
+}
+
+
+/*[clinic input]
+sys.addpendingcall
+
+    callback: object
+
+Schedule a *callback* to eventually execute in the main thread.
+[clinic start generated code]*/
+
+static PyObject *
+sys_addpendingcall_impl(PyObject *module, PyObject *callback)
+/*[clinic end generated code: output=8af6dede85199179 input=edaaec4bd3f2c753]*/
+{
+    if (Py_AddPendingCall(&_call_pending_pycallback, (void *)callback)) {
+        PyErr_SetString(PyExc_RuntimeError,
+                        "failed to add a pending callback");
+        return NULL;
+    }
+
+    Py_RETURN_NONE;
+}
+
 
 static PyMethodDef sys_methods[] = {
     /* Might as well keep this in alphabetic order */
@@ -1902,6 +1940,7 @@ static PyMethodDef sys_methods[] = {
     {"audit",           (PyCFunction)(void(*)(void))sys_audit, METH_FASTCALL, audit_doc },
     {"breakpointhook",  (PyCFunction)(void(*)(void))sys_breakpointhook,
      METH_FASTCALL | METH_KEYWORDS, breakpointhook_doc},
+    SYS_ADDPENDINGCALL_METHODDEF
     SYS_CALLSTATS_METHODDEF
     SYS__CLEAR_TYPE_CACHE_METHODDEF
     SYS__CURRENT_FRAMES_METHODDEF