diff -r fcc61327c86c Lib/datetime.py
--- a/Lib/datetime.py	Fri Feb 22 08:29:34 2013 +0200
+++ b/Lib/datetime.py	Sat Feb 23 21:19:29 2013 +0100
@@ -1059,6 +1059,25 @@
         """timezone info object"""
         return self._tzinfo
 
+    def __add__(self, other):
+        "Add a time and a timedelta"
+        if not isinstance(other, timedelta):
+            return NotImplemented
+
+        delta = timedelta(hours=self._hour,
+                          minutes=self._minute,
+                          seconds=self._second,
+                          microseconds=self._microsecond)
+
+        delta += other
+        hour, rem = divmod(delta.seconds, 3600)
+        minute, second = divmod(rem, 60)
+        if delta.days <= _MAXORDINAL:
+            return time(hour, minute, second,
+                        delta.microseconds,
+                        tzinfo=self._tzinfo)
+        raise OverflowError("result out of range")
+
     # Standard conversions, __hash__ (and helpers)
 
     # Comparisons of time objects with other.
diff -r fcc61327c86c Lib/test/datetimetester.py
--- a/Lib/test/datetimetester.py	Fri Feb 22 08:29:34 2013 +0200
+++ b/Lib/test/datetimetester.py	Sat Feb 23 21:19:29 2013 +0100
@@ -2330,6 +2330,21 @@
             self.assertRaises(TypeError, self.theclass,
                                          hour_byte + base[1:])
 
+    def test_computations(self):
+        a = self.theclass(0, 0, 0)
+        b = self.theclass(23, 59)
+
+        minute = timedelta(minutes=1)
+        hour = timedelta(hours=1)
+        week = timedelta(days=7)
+        self.assertEqual(a + minute, self.theclass(0, 1, 0))
+        self.assertEqual(b + minute + minute, self.theclass(0, 1))
+        self.assertEqual(b + minute, self.theclass(0, 0))
+        self.assertEqual(a + week, self.theclass(0))
+        self.assertEqual(a + week, self.theclass(0))
+        self.assertEqual(b + hour * 12, self.theclass(11, 59))
+
+
 # A mixin for classes with a tzinfo= argument.  Subclasses must define
 # theclass as a class atribute, and theclass(1, 1, 1, tzinfo=whatever)
 # must be legit (which is true for time and datetime).
diff -r fcc61327c86c Modules/_datetimemodule.c
--- a/Modules/_datetimemodule.c	Fri Feb 22 08:29:34 2013 +0200
+++ b/Modules/_datetimemodule.c	Sat Feb 23 21:19:29 2013 +0100
@@ -3821,6 +3821,53 @@
     return (TIME_GET_MINUTE(self)*60 - offsecs + TIME_GET_HOUR(self)*3600) != 0;
 }
 
+/* Force all the time fields into range
+ * the day argument is there just because I don't know how to normalize the
+ * hours without it.
+ */
+
+static void
+normalize_time(int *hour, int *minute, int *second, int *microsecond)
+{
+    int day = 0;
+    normalize_pair(second, microsecond, 1000000);
+    normalize_pair(minute, second, 60);
+    normalize_pair(hour, minute, 60);
+    normalize_pair(&day, hour, 24);
+}
+
+/*
+ * Time arithmetic
+ */
+
+/* time + timedelta -> time
+ *
+.*/
+static PyObject *
+add_time_timedelta(PyDateTime_Time *time, PyDateTime_Delta *delta)
+{
+    int hour = TIME_GET_HOUR(time);
+    int minute = TIME_GET_MINUTE(time);
+    int second = TIME_GET_SECOND(time) + GET_TD_SECONDS(delta);
+    int microsecond = TIME_GET_MICROSECOND(time) + GET_TD_MICROSECONDS(delta);
+
+    normalize_time(&hour, &minute, &second, &microsecond);
+
+    return new_time(hour, minute, second, microsecond,
+                    HASTZINFO(time) ? time->tzinfo : Py_None);
+}
+
+static PyObject *
+time_add(PyObject *left, PyObject *right)
+{
+    if (PyDelta_Check(right)) {
+        /* time + delta */
+        return add_time_timedelta((PyDateTime_Time *) left,
+                                   (PyDateTime_Delta *) right);
+    }
+    Py_RETURN_NOTIMPLEMENTED;
+}
+
 /* Pickle support, a simple use of __reduce__. */
 
 /* Let basestate be the non-tzinfo data string.
@@ -3889,7 +3936,7 @@
 a tzinfo subclass. The remaining arguments may be ints or longs.\n");
 
 static PyNumberMethods time_as_number = {
-    0,                                          /* nb_add */
+    time_add,                                   /* nb_add */
     0,                                          /* nb_subtract */
     0,                                          /* nb_multiply */
     0,                                          /* nb_remainder */