diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -423,6 +423,9 @@
 - Issue #19545: Avoid chained exceptions while passing stray % to
   time.strptime().  Initial patch by Claudiu Popa.
 
+- Issue #20177: Use argument clinic to parse arguments in
+  timemodule.c.  Patch by Nikolaus Rath.
+
 IDLE
 ----
 
diff --git a/Modules/timemodule.c b/Modules/timemodule.c
--- a/Modules/timemodule.c
+++ b/Modules/timemodule.c
@@ -49,6 +49,11 @@
 static OSVERSIONINFOEX winver;
 #endif
 
+/*[clinic input]
+module time
+[clinic start generated code]*/
+/*[clinic end generated code: checksum=da39a3ee5e6b4b0d3255bfef95601890afd80709]*/
+
 static PyObject *
 time_time(PyObject *self, PyObject *unused)
 {
@@ -157,16 +162,48 @@
 #endif
 
 #ifdef HAVE_CLOCK_GETTIME
+/*[clinic input]
+time.clock_gettime
+
+    clk_id: "i"
+    /
+
+Return the time of the specified clock clk_id
+[clinic start generated code]*/
+
+PyDoc_STRVAR(time_clock_gettime__doc__,
+"clock_gettime(clk_id)\n"
+"Return the time of the specified clock clk_id");
+
+#define TIME_CLOCK_GETTIME_METHODDEF    \
+    {"clock_gettime", (PyCFunction)time_clock_gettime, METH_VARARGS, time_clock_gettime__doc__},
+
 static PyObject *
-time_clock_gettime(PyObject *self, PyObject *args)
+time_clock_gettime_impl(PyModuleDef *module, int clk_id);
+
+static PyObject *
+time_clock_gettime(PyModuleDef *module, PyObject *args)
+{
+    PyObject *return_value = NULL;
+    int clk_id;
+
+    if (!PyArg_ParseTuple(args,
+        "i:clock_gettime",
+        &clk_id))
+        goto exit;
+    return_value = time_clock_gettime_impl(module, clk_id);
+
+exit:
+    return return_value;
+}
+
+static PyObject *
+time_clock_gettime_impl(PyModuleDef *module, int clk_id)
+/*[clinic end generated code: checksum=cefaa34b15ff90542d1ee0847c40314c254b1d7b]*/
 {
     int ret;
-    int clk_id;
     struct timespec tp;
 
-    if (!PyArg_ParseTuple(args, "i:clock_gettime", &clk_id))
-        return NULL;
-
     ret = clock_gettime((clockid_t)clk_id, &tp);
     if (ret != 0) {
         PyErr_SetFromErrno(PyExc_IOError);
@@ -175,24 +212,53 @@
     return PyFloat_FromDouble(tp.tv_sec + tp.tv_nsec * 1e-9);
 }
 
-PyDoc_STRVAR(clock_gettime_doc,
-"clock_gettime(clk_id) -> floating point number\n\
-\n\
-Return the time of the specified clock clk_id.");
+
+/*[clinic input]
+time.clock_settime
+
+    clk_id: "i"
+    obj: "O"
+    /
+
+Set the time of the specified clock clk_id.
+[clinic start generated code]*/
+
+PyDoc_STRVAR(time_clock_settime__doc__,
+"clock_settime(clk_id, obj)\n"
+"Set the time of the specified clock clk_id.");
+
+#define TIME_CLOCK_SETTIME_METHODDEF    \
+    {"clock_settime", (PyCFunction)time_clock_settime, METH_VARARGS, time_clock_settime__doc__},
 
 static PyObject *
-time_clock_settime(PyObject *self, PyObject *args)
+time_clock_settime_impl(PyModuleDef *module, int clk_id, PyObject *obj);
+
+static PyObject *
+time_clock_settime(PyModuleDef *module, PyObject *args)
 {
+    PyObject *return_value = NULL;
     int clk_id;
     PyObject *obj;
+
+    if (!PyArg_ParseTuple(args,
+        "iO:clock_settime",
+        &clk_id, &obj))
+        goto exit;
+    return_value = time_clock_settime_impl(module, clk_id, obj);
+
+exit:
+    return return_value;
+}
+
+static PyObject *
+time_clock_settime_impl(PyModuleDef *module, int clk_id, PyObject *obj)
+/*[clinic end generated code: checksum=c2ad16097bd86c6e8926b01f2488dc3c2bf6d3f6]*/
+{
     time_t tv_sec;
     long tv_nsec;
     struct timespec tp;
     int ret;
 
-    if (!PyArg_ParseTuple(args, "iO:clock_settime", &clk_id, &obj))
-        return NULL;
-
     if (_PyTime_ObjectToTimespec(obj, &tv_sec, &tv_nsec) == -1)
         return NULL;
     tp.tv_sec = tv_sec;
@@ -206,21 +272,49 @@
     Py_RETURN_NONE;
 }
 
-PyDoc_STRVAR(clock_settime_doc,
-"clock_settime(clk_id, time)\n\
-\n\
-Set the time of the specified clock clk_id.");
+
+/*[clinic input]
+time.clock_getres
+
+    clk_id: "i"
+    /
+
+Return the resolution (precision) of the specified clock clk_id.
+[clinic start generated code]*/
+
+PyDoc_STRVAR(time_clock_getres__doc__,
+"clock_getres(clk_id)\n"
+"Return the resolution (precision) of the specified clock clk_id.");
+
+#define TIME_CLOCK_GETRES_METHODDEF    \
+    {"clock_getres", (PyCFunction)time_clock_getres, METH_VARARGS, time_clock_getres__doc__},
 
 static PyObject *
-time_clock_getres(PyObject *self, PyObject *args)
+time_clock_getres_impl(PyModuleDef *module, int clk_id);
+
+static PyObject *
+time_clock_getres(PyModuleDef *module, PyObject *args)
+{
+    PyObject *return_value = NULL;
+    int clk_id;
+
+    if (!PyArg_ParseTuple(args,
+        "i:clock_getres",
+        &clk_id))
+        goto exit;
+    return_value = time_clock_getres_impl(module, clk_id);
+
+exit:
+    return return_value;
+}
+
+static PyObject *
+time_clock_getres_impl(PyModuleDef *module, int clk_id)
+/*[clinic end generated code: checksum=bbf728de562dbd7d909dc0f6396d8368d98c16c6]*/
 {
     int ret;
-    int clk_id;
     struct timespec tp;
 
-    if (!PyArg_ParseTuple(args, "i:clock_getres", &clk_id))
-        return NULL;
-
     ret = clock_getres((clockid_t)clk_id, &tp);
     if (ret != 0) {
         PyErr_SetFromErrno(PyExc_IOError);
@@ -229,19 +323,51 @@
 
     return PyFloat_FromDouble(tp.tv_sec + tp.tv_nsec * 1e-9);
 }
-
-PyDoc_STRVAR(clock_getres_doc,
-"clock_getres(clk_id) -> floating point number\n\
-\n\
-Return the resolution (precision) of the specified clock clk_id.");
 #endif   /* HAVE_CLOCK_GETTIME */
 
+/*[clinic input]
+time.sleep
+
+    secs: "d"
+    /
+
+Delay execution for a given number of seconds.
+
+The argument may be a floating point number for subsecond precision.
+[clinic start generated code]*/
+
+PyDoc_STRVAR(time_sleep__doc__,
+"sleep(secs)\n"
+"Delay execution for a given number of seconds.\n"
+"\n"
+"The argument may be a floating point number for subsecond precision.");
+
+#define TIME_SLEEP_METHODDEF    \
+    {"sleep", (PyCFunction)time_sleep, METH_VARARGS, time_sleep__doc__},
+
 static PyObject *
-time_sleep(PyObject *self, PyObject *args)
+time_sleep_impl(PyModuleDef *module, double secs);
+
+static PyObject *
+time_sleep(PyModuleDef *module, PyObject *args)
 {
+    PyObject *return_value = NULL;
     double secs;
-    if (!PyArg_ParseTuple(args, "d:sleep", &secs))
-        return NULL;
+
+    if (!PyArg_ParseTuple(args,
+        "d:sleep",
+        &secs))
+        goto exit;
+    return_value = time_sleep_impl(module, secs);
+
+exit:
+    return return_value;
+}
+
+static PyObject *
+time_sleep_impl(PyModuleDef *module, double secs)
+/*[clinic end generated code: checksum=66cd8e8be8e7d3a8d1732ba218de5baf175c22dd]*/
+{
     if (secs < 0) {
         PyErr_SetString(PyExc_ValueError,
                         "sleep length must be non-negative");
@@ -253,11 +379,6 @@
     return Py_None;
 }
 
-PyDoc_STRVAR(sleep_doc,
-"sleep(seconds)\n\
-\n\
-Delay execution for a given number of seconds.  The argument may be\n\
-a floating point number for subsecond precision.");
 
 static PyStructSequence_Field struct_time_type_fields[] = {
     {"tm_year", "year, for example, 1993"},
@@ -565,10 +686,53 @@
 #define time_strlen strlen
 #endif
 
+/*[clinic input]
+time.strftime
+
+    format_arg: "U"
+    tup: "O"=None
+    /
+
+Convert a time tuple to a string according to a format specification.
+
+See the library reference manual for formatting codes. When the time tuple
+is not present, current time as returned by localtime() is used.
+[clinic start generated code]*/
+
+PyDoc_STRVAR(time_strftime__doc__,
+"strftime(format_arg, tup=None)\n"
+"Convert a time tuple to a string according to a format specification.\n"
+"\n"
+"See the library reference manual for formatting codes. When the time tuple\n"
+"is not present, current time as returned by localtime() is used.");
+
+#define TIME_STRFTIME_METHODDEF    \
+    {"strftime", (PyCFunction)time_strftime, METH_VARARGS, time_strftime__doc__},
+
 static PyObject *
-time_strftime(PyObject *self, PyObject *args)
+time_strftime_impl(PyModuleDef *module, PyObject *format_arg, PyObject *tup);
+
+static PyObject *
+time_strftime(PyModuleDef *module, PyObject *args)
 {
-    PyObject *tup = NULL;
+    PyObject *return_value = NULL;
+    PyObject *format_arg;
+    PyObject *tup = Py_None;
+
+    if (!PyArg_ParseTuple(args,
+        "U|O:strftime",
+        &format_arg, &tup))
+        goto exit;
+    return_value = time_strftime_impl(module, format_arg, tup);
+
+exit:
+    return return_value;
+}
+
+static PyObject *
+time_strftime_impl(PyModuleDef *module, PyObject *format_arg, PyObject *tup)
+/*[clinic end generated code: checksum=90fb8736ec1e85fe5dc7cbe259ce990e5ee8e35d]*/
+{
     struct tm buf;
     const time_char *fmt;
 #ifdef HAVE_WCSFTIME
@@ -576,7 +740,6 @@
 #else
     PyObject *format;
 #endif
-    PyObject *format_arg;
     size_t fmtlen, buflen;
     time_char *outbuf = NULL;
     size_t i;
@@ -584,12 +747,6 @@
 
     memset((void *) &buf, '\0', sizeof(buf));
 
-    /* Will always expect a unicode string to be passed as format.
-       Given that there's no str type anymore in py3k this seems safe.
-    */
-    if (!PyArg_ParseTuple(args, "U|O:strftime", &format_arg, &tup))
-        return NULL;
-
     if (tup == NULL) {
         time_t tt = time(NULL);
         if (pylocaltime(&tt, &buf) == -1)
@@ -717,13 +874,6 @@
 
 #undef time_char
 #undef format_time
-PyDoc_STRVAR(strftime_doc,
-"strftime(format[, tuple]) -> string\n\
-\n\
-Convert a time tuple to a string according to a format specification.\n\
-See the library reference manual for formatting codes. When the time tuple\n\
-is not present, current time as returned by localtime() is used.\n\
-\n" STRFTIME_FORMAT_CODES);
 #endif /* HAVE_STRFTIME */
 
 static PyObject *
@@ -1396,11 +1546,11 @@
     {"clock",           time_clock, METH_NOARGS, clock_doc},
 #endif
 #ifdef HAVE_CLOCK_GETTIME
-    {"clock_gettime",   time_clock_gettime, METH_VARARGS, clock_gettime_doc},
-    {"clock_settime",   time_clock_settime, METH_VARARGS, clock_settime_doc},
-    {"clock_getres",    time_clock_getres, METH_VARARGS, clock_getres_doc},
+    TIME_CLOCK_GETTIME_METHODDEF
+    TIME_CLOCK_SETTIME_METHODDEF
+    TIME_CLOCK_GETRES_METHODDEF
 #endif
-    {"sleep",           time_sleep, METH_VARARGS, sleep_doc},
+    TIME_SLEEP_METHODDEF
     {"gmtime",          time_gmtime, METH_VARARGS, gmtime_doc},
     {"localtime",       time_localtime, METH_VARARGS, localtime_doc},
     {"asctime",         time_asctime, METH_VARARGS, asctime_doc},
@@ -1409,7 +1559,7 @@
     {"mktime",          time_mktime, METH_O, mktime_doc},
 #endif
 #ifdef HAVE_STRFTIME
-    {"strftime",        time_strftime, METH_VARARGS, strftime_doc},
+    TIME_STRFTIME_METHODDEF
 #endif
     {"strptime",        time_strptime, METH_VARARGS, strptime_doc},
 #ifdef HAVE_WORKING_TZSET