diff --git a/rtc_base/event.cc b/rtc_base/event.cc
index ff4faadd67..9e38159b66 100644
--- a/rtc_base/event.cc
+++ b/rtc_base/event.cc
@@ -52,11 +52,34 @@ bool Event::Wait(int milliseconds) {
 
 #elif defined(WEBRTC_POSIX)
 
+// On MacOS, clock_gettime is available from version 10.12, and on
+// iOS, from version 10.0. So we can't use it yet.
+#if defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
+#define USE_CLOCK_GETTIME 0
+#define USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP 0
+// On Android, pthread_condattr_setclock is available from version 21. By
+// default, we target a new enough version for 64-bit platforms but not for
+// 32-bit platforms. For older versions, use
+// pthread_cond_timedwait_monotonic_np.
+#elif defined(WEBRTC_ANDROID) && (__ANDROID_API__ < 21)
+#define USE_CLOCK_GETTIME 1
+#define USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP 1
+#else
+#define USE_CLOCK_GETTIME 1
+#define USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP 0
+#endif
+
 Event::Event(bool manual_reset, bool initially_signaled)
     : is_manual_reset_(manual_reset),
       event_status_(initially_signaled) {
   RTC_CHECK(pthread_mutex_init(&event_mutex_, nullptr) == 0);
-  RTC_CHECK(pthread_cond_init(&event_cond_, nullptr) == 0);
+  pthread_condattr_t cond_attr;
+  RTC_CHECK(pthread_condattr_init(&cond_attr) == 0);
+#if USE_CLOCK_GETTIME && !USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP
+  RTC_CHECK(pthread_condattr_setclock(&cond_attr, CLOCK_MONOTONIC) == 0);
+#endif
+  RTC_CHECK(pthread_cond_init(&event_cond_, &cond_attr) == 0);
+  pthread_condattr_destroy(&cond_attr);
 }
 
 Event::~Event() {
@@ -82,14 +105,17 @@ bool Event::Wait(int milliseconds) {
 
   struct timespec ts;
   if (milliseconds != kForever) {
-    // Converting from seconds and microseconds (1e-6) plus
-    // milliseconds (1e-3) to seconds and nanoseconds (1e-9).
-
+#if USE_CLOCK_GETTIME
+    clock_gettime(CLOCK_MONOTONIC, &ts);
+#else
     struct timeval tv;
     gettimeofday(&tv, nullptr);
+    ts.tv_sec = tv.tv_sec;
+    ts.tv_nsec = tv.tv_usec * 1000;
+#endif
 
-    ts.tv_sec = tv.tv_sec + (milliseconds / 1000);
-    ts.tv_nsec = tv.tv_usec * 1000 + (milliseconds % 1000) * 1000000;
+    ts.tv_sec += (milliseconds / 1000);
+    ts.tv_nsec += (milliseconds % 1000) * 1000000;
 
     // Handle overflow.
     if (ts.tv_nsec >= 1000000000) {
@@ -101,7 +127,12 @@ bool Event::Wait(int milliseconds) {
   pthread_mutex_lock(&event_mutex_);
   if (milliseconds != kForever) {
     while (!event_status_ && error == 0) {
+#if USE_PTHREAD_COND_TIMEDWAIT_MONOTONIC_NP
+      error =
+          pthread_cond_timedwait_monotonic_np(&event_cond_, &event_mutex_, &ts);
+#else
       error = pthread_cond_timedwait(&event_cond_, &event_mutex_, &ts);
+#endif
     }
   } else {
     while (!event_status_ && error == 0)