diff -r 21f6c4378846 Lib/multiprocessing/synchronize.py
--- a/Lib/multiprocessing/synchronize.py	Mon Oct 26 04:37:55 2015 -0400
+++ b/Lib/multiprocessing/synchronize.py	Thu Nov 05 22:20:10 2015 +0000
@@ -259,7 +259,12 @@
 
         try:
             # wait for notification or timeout
-            return self._wait_semaphore.acquire(True, timeout)
+            notified = self._wait_semaphore.acquire(True, timeout)
+        except:
+            notified = False
+            raise
+        else:
+            return notified
         finally:
             # indicate that this thread has woken
             self._woken_count.release()
@@ -268,16 +273,15 @@
             for i in range(count):
                 self._lock.acquire()
 
+            # decrement counters since wasn't notified
+            if not notified:
+                self._woken_count.acquire(False)
+                self._sleeping_count.acquire(False)
+
     def notify(self):
         assert self._lock._semlock._is_mine(), 'lock is not owned'
         assert not self._wait_semaphore.acquire(False)
 
-        # to take account of timeouts since last notify() we subtract
-        # woken_count from sleeping_count and rezero woken_count
-        while self._woken_count.acquire(False):
-            res = self._sleeping_count.acquire(False)
-            assert res
-
         if self._sleeping_count.acquire(False): # try grabbing a sleeper
             self._wait_semaphore.release()      # wake up one sleeper
             self._woken_count.acquire()         # wait for the sleeper to wake
@@ -289,12 +293,6 @@
         assert self._lock._semlock._is_mine(), 'lock is not owned'
         assert not self._wait_semaphore.acquire(False)
 
-        # to take account of timeouts since last notify*() we subtract
-        # woken_count from sleeping_count and rezero woken_count
-        while self._woken_count.acquire(False):
-            res = self._sleeping_count.acquire(False)
-            assert res
-
         sleepers = 0
         while self._sleeping_count.acquire(False):
             self._wait_semaphore.release()        # wake up one sleeper
diff -r 21f6c4378846 Lib/test/_test_multiprocessing.py
--- a/Lib/test/_test_multiprocessing.py	Mon Oct 26 04:37:55 2015 -0400
+++ b/Lib/test/_test_multiprocessing.py	Thu Nov 05 22:20:10 2015 +0000
@@ -1103,6 +1103,34 @@
         p.start()
         self.assertEqual(wait(), True)
 
+    @classmethod
+    def _test_issue_25469_f(cls, event):
+        while not event.wait(0):
+            pass
+
+    def test_issue_25469(self):
+        event = self.Event()
+        procs = [self.Process(target=self._test_issue_25469_f, args=(event,))
+                 for _ in range(3)]
+        set_ = TimingWrapper(event.set)
+
+        for p in procs:
+            p.daemon = True
+            p.start()
+        # allow for child process to make many Event.wait() calls with timeout
+        time.sleep(3)
+        set_()
+
+        for p in procs:
+            p.join(1)
+            self.assertFalse(p.is_alive())
+
+        t_after_waits = set_.elapsed
+        set_()
+        # Timed-out calls to Event.wait() should not result in Event.set()
+        # taking any longer than when it's called otherwise
+        self.assertAlmostEqual(t_after_waits, set_.elapsed, 2)
+
 #
 # Tests for Barrier - adapted from tests in test/lock_tests.py
 #