diff --git a/call/video_config.cc b/call/video_config.cc
index 982c013e46..35fcd3e9ba 100644
--- a/call/video_config.cc
+++ b/call/video_config.cc
@@ -24,6 +24,7 @@ VideoStream::VideoStream()
       target_bitrate_bps(-1),
       max_bitrate_bps(-1),
       max_qp(-1) {}
+VideoStream::VideoStream(const VideoStream& other) = default;
 
 VideoStream::~VideoStream() = default;
 
diff --git a/call/video_config.h b/call/video_config.h
index 2276e785dd..038cdb2b5b 100644
--- a/call/video_config.h
+++ b/call/video_config.h
@@ -26,6 +26,7 @@ namespace webrtc {
 struct VideoStream {
   VideoStream();
   ~VideoStream();
+  VideoStream(const VideoStream& other);
   std::string ToString() const;
 
   size_t width;
@@ -39,6 +40,9 @@ struct VideoStream {
 
   int max_qp;
 
+  // TODO(bugs.webrtc.org/8653): Support active per-simulcast layer.
+  bool active;
+
   // Bitrate thresholds for enabling additional temporal layers. Since these are
   // thresholds in between layers, we have one additional layer. One threshold
   // gives two temporal layers, one below the threshold and one above, two give
@@ -146,6 +150,11 @@ class VideoEncoderConfig {
   // The bitrate priority used for all VideoStreams.
   double bitrate_priority;
 
+  // The simulcast layer's configurations set by the application for this video
+  // sender. These are modified by the video_stream_factory before being passed
+  // down to lower layers for the video encoding.
+  std::vector<VideoStream> simulcast_layers;
+
   // Max number of encoded VideoStreams to produce.
   size_t number_of_streams;