diff --git a/modules/rtp_rtcp/BUILD.gn b/modules/rtp_rtcp/BUILD.gn
index a115f1d098..4bc68ebf29 100644
--- a/modules/rtp_rtcp/BUILD.gn
+++ b/modules/rtp_rtcp/BUILD.gn
@@ -638,6 +638,7 @@ if (rtc_include_tests) {
       "../../api:frame_transformer_factory",
       "../../api:libjingle_peerconnection_api",
       "../../api:mock_frame_encryptor",
+      "../../api:mock_transformable_video_frame",
       "../../api:rtp_headers",
       "../../api:rtp_packet_info",
       "../../api:rtp_parameters",
diff --git a/modules/rtp_rtcp/source/rtp_video_stream_receiver_frame_transformer_delegate.cc b/modules/rtp_rtcp/source/rtp_video_stream_receiver_frame_transformer_delegate.cc
index 8254341628..6e915bf758 100644
--- a/modules/rtp_rtcp/source/rtp_video_stream_receiver_frame_transformer_delegate.cc
+++ b/modules/rtp_rtcp/source/rtp_video_stream_receiver_frame_transformer_delegate.cc
@@ -115,13 +115,44 @@ void RtpVideoStreamReceiverFrameTransformerDelegate::OnTransformedFrame(
 void RtpVideoStreamReceiverFrameTransformerDelegate::ManageFrame(
     std::unique_ptr<TransformableFrameInterface> frame) {
   RTC_DCHECK_RUN_ON(&network_sequence_checker_);
-  RTC_CHECK_EQ(frame->GetDirection(),
-               TransformableFrameInterface::Direction::kReceiver);
   if (!receiver_)
     return;
-  auto transformed_frame = absl::WrapUnique(
-      static_cast<TransformableVideoReceiverFrame*>(frame.release()));
-  receiver_->ManageFrame(std::move(*transformed_frame).ExtractFrame());
+  if (frame->GetDirection() ==
+      TransformableFrameInterface::Direction::kReceiver) {
+    auto transformed_frame = absl::WrapUnique(
+        static_cast<TransformableVideoReceiverFrame*>(frame.release()));
+    receiver_->ManageFrame(std::move(*transformed_frame).ExtractFrame());
+  } else {
+    RTC_CHECK_EQ(frame->GetDirection(),
+                 TransformableFrameInterface::Direction::kSender);
+    // This frame is actually an frame encoded locally, to be sent, but has been
+    // fed back into this receiver's insertable stream writer.
+    // Create a reasonable RtpFrameObject as if this frame had been received
+    // over RTP, reusing the frameId as an analog for the RTP sequence number,
+    // and handle it as if it had been received.
+    // TODO(https://crbug.com/1250638): Rewrite the receiver's codepaths after
+    // this transform to be transport-agnostic and not need a faked rtp
+    // sequence number.
+
+    auto transformed_frame = absl::WrapUnique(
+        static_cast<TransformableVideoFrameInterface*>(frame.release()));
+    VideoFrameMetadata metadata = transformed_frame->Metadata();
+    RTPVideoHeader video_header = RTPVideoHeader::FromMetadata(metadata);
+    VideoSendTiming timing;
+    rtc::ArrayView<const uint8_t> data = transformed_frame->GetData();
+    receiver_->ManageFrame(std::make_unique<RtpFrameObject>(
+        /*first_seq_num=*/metadata.GetFrameId().value_or(0),
+        /*last_seq_num=*/metadata.GetFrameId().value_or(0),
+        /*markerBit=*/video_header.is_last_frame_in_picture,
+        /*times_nacked=*/0,
+        /*first_packet_received_time=*/0,
+        /*last_packet_received_time=*/0,
+        /*rtp_timestamp=*/transformed_frame->GetTimestamp(),
+        /*ntp_time_ms=*/0, timing, transformed_frame->GetPayloadType(),
+        metadata.GetCodec(), metadata.GetRotation(), metadata.GetContentType(),
+        video_header, video_header.color_space, RtpPacketInfos(),
+        EncodedImageBuffer::Create(data.data(), data.size())));
+  }
 }
 
 }  // namespace webrtc
diff --git a/modules/rtp_rtcp/source/rtp_video_stream_receiver_frame_transformer_delegate_unittest.cc b/modules/rtp_rtcp/source/rtp_video_stream_receiver_frame_transformer_delegate_unittest.cc
index 707970e14f..0fdc503e46 100644
--- a/modules/rtp_rtcp/source/rtp_video_stream_receiver_frame_transformer_delegate_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_video_stream_receiver_frame_transformer_delegate_unittest.cc
@@ -17,6 +17,7 @@
 
 #include "absl/memory/memory.h"
 #include "api/call/transport.h"
+#include "api/test/mock_transformable_video_frame.h"
 #include "api/units/timestamp.h"
 #include "call/video_receive_stream.h"
 #include "modules/rtp_rtcp/source/rtp_descriptor_authentication.h"
@@ -31,6 +32,7 @@ namespace {
 using ::testing::_;
 using ::testing::ElementsAre;
 using ::testing::NiceMock;
+using ::testing::Return;
 using ::testing::SaveArg;
 
 std::unique_ptr<RtpFrameObject> CreateRtpFrameObject(
@@ -175,5 +177,43 @@ TEST(RtpVideoStreamReceiverFrameTransformerDelegateTest,
   delegate->TransformFrame(CreateRtpFrameObject(video_header, csrcs));
 }
 
+TEST(RtpVideoStreamReceiverFrameTransformerDelegateTest,
+     SenderFramesAreConvertedToReceiverFrames) {
+  rtc::AutoThread main_thread_;
+  TestRtpVideoFrameReceiver receiver;
+  auto mock_frame_transformer =
+      rtc::make_ref_counted<NiceMock<MockFrameTransformer>>();
+  auto delegate =
+      rtc::make_ref_counted<RtpVideoStreamReceiverFrameTransformerDelegate>(
+          &receiver, mock_frame_transformer, rtc::Thread::Current(),
+          /*remote_ssrc*/ 1111);
+
+  auto mock_sender_frame =
+      std::make_unique<NiceMock<MockTransformableVideoFrame>>();
+  ON_CALL(*mock_sender_frame, GetDirection)
+      .WillByDefault(Return(TransformableFrameInterface::Direction::kSender));
+  VideoFrameMetadata metadata;
+  metadata.SetCodec(kVideoCodecVP8);
+  metadata.SetRTPVideoHeaderCodecSpecifics(RTPVideoHeaderVP8());
+  ON_CALL(*mock_sender_frame, Metadata).WillByDefault(Return(metadata));
+  rtc::scoped_refptr<EncodedImageBufferInterface> buffer =
+      EncodedImageBuffer::Create(1);
+  ON_CALL(*mock_sender_frame, GetData)
+      .WillByDefault(Return(rtc::ArrayView<const uint8_t>(*buffer)));
+
+  rtc::scoped_refptr<TransformedFrameCallback> callback;
+  EXPECT_CALL(*mock_frame_transformer, RegisterTransformedFrameSinkCallback)
+      .WillOnce(SaveArg<0>(&callback));
+  delegate->Init();
+  ASSERT_TRUE(callback);
+
+  EXPECT_CALL(receiver, ManageFrame)
+      .WillOnce([&](std::unique_ptr<RtpFrameObject> frame) {
+        EXPECT_EQ(frame->codec_type(), metadata.GetCodec());
+      });
+  callback->OnTransformedFrame(std::move(mock_sender_frame));
+  rtc::ThreadManager::ProcessAllMessageQueuesForTesting();
+}
+
 }  // namespace
 }  // namespace webrtc