diff --git a/api/video/video_stream_encoder_observer.h b/api/video/video_stream_encoder_observer.h
index 0d639f3c05..9fd462ca3e 100644
--- a/api/video/video_stream_encoder_observer.h
+++ b/api/video/video_stream_encoder_observer.h
@@ -95,6 +95,11 @@ class VideoStreamEncoderObserver : public CpuOveruseMetricsObserver {
       const VideoCodec& codec,
       const VideoBitrateAllocation& allocation) {}
 
+  // Informes observer if an internal encoder scaler has reduced video
+  // resolution or not. |is_scaled| is a flag indicating if the video is scaled
+  // down.
+  virtual void OnEncoderInternalScalerUpdate(bool is_scaled) {}
+
   // TODO(nisse): VideoStreamEncoder wants to query the stats, which makes this
   // not a pure observer. GetInputFrameRate is needed for the cpu adaptation, so
   // can be deleted if that responsibility is moved out to a VideoStreamAdaptor
diff --git a/video/send_statistics_proxy.cc b/video/send_statistics_proxy.cc
index 094baa3157..60d84f14c7 100644
--- a/video/send_statistics_proxy.cc
+++ b/video/send_statistics_proxy.cc
@@ -148,6 +148,7 @@ SendStatisticsProxy::SendStatisticsProxy(
       last_num_simulcast_streams_(0),
       last_spatial_layer_use_{},
       bw_limited_layers_(false),
+      internal_encoder_scaler_(false),
       uma_container_(
           new UmaSamplesContainer(GetUmaPrefix(content_type_), stats_, clock)) {
 }
@@ -1083,7 +1084,7 @@ void SendStatisticsProxy::UpdateAdaptationStats() {
                         cpu_counts_.num_framerate_reductions > 0;
   bool is_bandwidth_limited = quality_counts_.num_resolution_reductions > 0 ||
                               quality_counts_.num_framerate_reductions > 0 ||
-                              bw_limited_layers_;
+                              bw_limited_layers_ || internal_encoder_scaler_;
   if (is_bandwidth_limited) {
     // We may be both CPU limited and bandwidth limited at the same time but
     // there is no way to express this in standardized stats. Heuristically,
@@ -1117,6 +1118,10 @@ void SendStatisticsProxy::UpdateAdaptationStats() {
       }
     }
   }
+  if (internal_encoder_scaler_) {
+    stats_.bw_limited_resolution = true;
+  }
+
   stats_.quality_limitation_reason =
       quality_limitation_reason_tracker_.current_reason();
 
@@ -1164,6 +1169,15 @@ void SendStatisticsProxy::OnBitrateAllocationUpdated(
   last_num_simulcast_streams_ = num_simulcast_streams;
 }
 
+// Informes observer if an internal encoder scaler has reduced video
+// resolution or not. |is_scaled| is a flag indicating if the video is scaled
+// down.
+void SendStatisticsProxy::OnEncoderInternalScalerUpdate(bool is_scaled) {
+  rtc::CritScope lock(&crit_);
+  internal_encoder_scaler_ = is_scaled;
+  UpdateAdaptationStats();
+}
+
 // TODO(asapersson): Include fps changes.
 void SendStatisticsProxy::OnInitialQualityResolutionAdaptDown() {
   rtc::CritScope lock(&crit_);
diff --git a/video/send_statistics_proxy.h b/video/send_statistics_proxy.h
index a67725e17a..abe39992cd 100644
--- a/video/send_statistics_proxy.h
+++ b/video/send_statistics_proxy.h
@@ -78,6 +78,8 @@ class SendStatisticsProxy : public VideoStreamEncoderObserver,
       const VideoCodec& codec,
       const VideoBitrateAllocation& allocation) override;
 
+  void OnEncoderInternalScalerUpdate(bool is_scaled) override;
+
   void OnMinPixelLimitReached() override;
   void OnInitialQualityResolutionAdaptDown() override;
 
@@ -264,6 +266,8 @@ class SendStatisticsProxy : public VideoStreamEncoderObserver,
   // Indicates if the latest bitrate allocation had layers disabled by low
   // available bandwidth.
   bool bw_limited_layers_ RTC_GUARDED_BY(crit_);
+  // Indicastes if the encoder internally downscales input image.
+  bool internal_encoder_scaler_ RTC_GUARDED_BY(crit_);
   AdaptationSteps cpu_counts_ RTC_GUARDED_BY(crit_);
   AdaptationSteps quality_counts_ RTC_GUARDED_BY(crit_);
 
diff --git a/video/send_statistics_proxy_unittest.cc b/video/send_statistics_proxy_unittest.cc
index db5c94b5cb..3f5ebd53b4 100644
--- a/video/send_statistics_proxy_unittest.cc
+++ b/video/send_statistics_proxy_unittest.cc
@@ -2147,6 +2147,15 @@ TEST_F(SendStatisticsProxyTest, GetStatsReportsBandwidthLimitedResolution) {
   allocation.set_bw_limited(true);
   statistics_proxy_->OnBitrateAllocationUpdated(codec, allocation);
   EXPECT_TRUE(statistics_proxy_->GetStats().bw_limited_resolution);
+
+  // Revert for the next test.
+  allocation.set_bw_limited(false);
+  statistics_proxy_->OnBitrateAllocationUpdated(codec, allocation);
+  EXPECT_FALSE(statistics_proxy_->GetStats().bw_limited_resolution);
+
+  // Internal encoder scaler reduced resolution.
+  statistics_proxy_->OnEncoderInternalScalerUpdate(/*scaled=*/true);
+  EXPECT_TRUE(statistics_proxy_->GetStats().bw_limited_resolution);
 }
 
 TEST_F(SendStatisticsProxyTest, GetStatsReportsTargetMediaBitrate) {
diff --git a/video/video_quality_test.cc b/video/video_quality_test.cc
index b870f7c793..826567c21f 100644
--- a/video/video_quality_test.cc
+++ b/video/video_quality_test.cc
@@ -870,6 +870,7 @@ void VideoQualityTest::SetupVideo(Transport* send_transport,
         VideoCodecVP9 vp9_settings = VideoEncoder::GetDefaultVp9Settings();
         vp9_settings.denoisingOn = false;
         vp9_settings.frameDroppingOn = false;
+        vp9_settings.automaticResizeOn = false;
         vp9_settings.numberOfTemporalLayers = static_cast<unsigned char>(
             params_.video[video_idx].num_temporal_layers);
         vp9_settings.numberOfSpatialLayers = static_cast<unsigned char>(
@@ -892,6 +893,7 @@ void VideoQualityTest::SetupVideo(Transport* send_transport,
       vp9_settings.numberOfSpatialLayers =
           static_cast<unsigned char>(params_.ss[video_idx].num_spatial_layers);
       vp9_settings.interLayerPred = params_.ss[video_idx].inter_layer_pred;
+      vp9_settings.automaticResizeOn = false;
       video_encoder_configs_[video_idx].encoder_specific_settings =
           new rtc::RefCountedObject<
               VideoEncoderConfig::Vp9EncoderSpecificSettings>(vp9_settings);
@@ -904,7 +906,9 @@ void VideoQualityTest::SetupVideo(Transport* send_transport,
                 VideoEncoderConfig::Vp8EncoderSpecificSettings>(vp8_settings);
       } else if (params_.video[video_idx].codec == "VP9") {
         VideoCodecVP9 vp9_settings = VideoEncoder::GetDefaultVp9Settings();
-        vp9_settings.automaticResizeOn = true;
+        // Only enable quality scaler for single spatial layer.
+        vp9_settings.automaticResizeOn =
+            params_.ss[video_idx].num_spatial_layers == 1;
         video_encoder_configs_[video_idx].encoder_specific_settings =
             new rtc::RefCountedObject<
                 VideoEncoderConfig::Vp9EncoderSpecificSettings>(vp9_settings);
diff --git a/video/video_send_stream_tests.cc b/video/video_send_stream_tests.cc
index 7ceb9db136..27bf0f08bf 100644
--- a/video/video_send_stream_tests.cc
+++ b/video/video_send_stream_tests.cc
@@ -3479,6 +3479,7 @@ void VideoSendStreamTest::TestVp9NonFlexMode(uint8_t num_temporal_layers,
 
       vp9_settings_.flexibleMode = false;
       vp9_settings_.frameDroppingOn = false;
+      vp9_settings_.automaticResizeOn = false;
       vp9_settings_.keyFrameInterval = kKeyFrameInterval;
       vp9_settings_.numberOfTemporalLayers = num_temporal_layers_;
       vp9_settings_.numberOfSpatialLayers = num_spatial_layers_;
diff --git a/video/video_stream_encoder.cc b/video/video_stream_encoder.cc
index 58fba37bae..d9eda8e302 100644
--- a/video/video_stream_encoder.cc
+++ b/video/video_stream_encoder.cc
@@ -169,6 +169,7 @@ VideoBitrateAllocation UpdateAllocationFromEncoderInfo(
   new_allocation.set_bw_limited(allocation.is_bw_limited());
   return new_allocation;
 }
+
 }  //  namespace
 
 const int VideoStreamEncoder::kDefaultLastFrameInfoWidth = 176;
@@ -1360,6 +1361,37 @@ EncodedImageCallback::Result VideoStreamEncoder::OnEncodedImage(
   RTC_CHECK(videocontenttypehelpers::SetSimulcastId(
       &image_copy.content_type_, static_cast<uint8_t>(spatial_idx + 1)));
 
+  // Currently internal quality scaler is used for VP9 instead of webrtc qp
+  // scaler (in no-svc case or if only a single spatial layer is encoded).
+  // It has to be explicitly detected and reported to adaptation metrics.
+  // Post a task because |send_codec_| requires |encoder_queue_| lock.
+  unsigned int image_width = image_copy._encodedWidth;
+  unsigned int image_height = image_copy._encodedHeight;
+  VideoCodecType codec = codec_specific_info
+                             ? codec_specific_info->codecType
+                             : VideoCodecType::kVideoCodecGeneric;
+  encoder_queue_.PostTask([this, codec, image_width, image_height] {
+    RTC_DCHECK_RUN_ON(&encoder_queue_);
+    if (codec == VideoCodecType::kVideoCodecVP9 &&
+        send_codec_.VP9()->automaticResizeOn) {
+      unsigned int expected_width = send_codec_.width;
+      unsigned int expected_height = send_codec_.height;
+      int num_active_layers = 0;
+      for (int i = 0; i < send_codec_.VP9()->numberOfSpatialLayers; ++i) {
+        if (send_codec_.spatialLayers[i].active) {
+          ++num_active_layers;
+          expected_width = send_codec_.spatialLayers[i].width;
+          expected_height = send_codec_.spatialLayers[i].height;
+        }
+      }
+      RTC_DCHECK_LE(num_active_layers, 1)
+          << "VP9 quality scaling is enabled for "
+             "SVC with several active layers.";
+      encoder_stats_observer_->OnEncoderInternalScalerUpdate(
+          image_width < expected_width || image_height < expected_height);
+    }
+  });
+
   // Encoded is called on whatever thread the real encoder implementation run
   // on. In the case of hardware encoders, there might be several encoders
   // running in parallel on different threads.