diff --git a/video/video_stream_encoder.cc b/video/video_stream_encoder.cc
index ea59b0aba0..b4b5af556d 100644
--- a/video/video_stream_encoder.cc
+++ b/video/video_stream_encoder.cc
@@ -336,6 +336,7 @@ class VideoStreamEncoder::VideoSourceProxy {
     }
     // Limit to configured max framerate.
     wants.max_framerate_fps = std::min(max_framerate_, wants.max_framerate_fps);
+    wants.partial_frames = true;
     return wants;
   }
 
@@ -713,8 +714,24 @@ void VideoStreamEncoder::ConfigureQualityScaler() {
 
 void VideoStreamEncoder::OnFrame(const VideoFrame& video_frame) {
   RTC_DCHECK_RUNS_SERIALIZED(&incoming_frame_race_checker_);
+
+  const VideoFrame::PartialFrameDescription* partial_desc =
+      video_frame.partial_frame_description();
   VideoFrame incoming_frame = video_frame;
 
+  if (video_frame.cache_buffer_for_partial_updates()) {
+    VideoFrameBuffer* input_buffer = video_frame.video_frame_buffer();
+    if (!partial_frame_assembler_.ApplyPartialUpdate(
+            input_buffer, &incoming_frame, partial_desc)) {
+      // Can't apply new image to the cached buffer because of some error.
+      // Nothing sensible to encode.
+      // Detailed error message is already logged by |ApplyPartialUpdate()|.
+      return;
+    }
+  } else {
+    partial_frame_assembler_.Reset();
+  }
+
   // Local time in webrtc time base.
   int64_t current_time_us = clock_->TimeInMicroseconds();
   int64_t current_time_ms = current_time_us / rtc::kNumMicrosecsPerMillisec;
diff --git a/video/video_stream_encoder.h b/video/video_stream_encoder.h
index 577ca5b562..0c9cb3c828 100644
--- a/video/video_stream_encoder.h
+++ b/video/video_stream_encoder.h
@@ -33,6 +33,7 @@
 #include "rtc_base/sequenced_task_checker.h"
 #include "rtc_base/task_queue.h"
 #include "video/overuse_frame_detector.h"
+#include "video/partial_frame_assembler.h"
 
 namespace webrtc {
 
@@ -295,6 +296,9 @@ class VideoStreamEncoder : public VideoStreamEncoderInterface,
   // the worker thread.
   std::atomic<int> pending_frame_drops_;
 
+  PartialFrameAssembler partial_frame_assembler_
+      RTC_GUARDED_BY(incoming_frame_race_checker_);
+
   // All public methods are proxied to |encoder_queue_|. It must must be
   // destroyed first to make sure no tasks are run that use other members.
   rtc::TaskQueue encoder_queue_;