diff --git a/quic/core/http/quic_receive_control_stream.cc b/quic/core/http/quic_receive_control_stream.cc
index 85585bd..17a3c82 100644
--- a/quic/core/http/quic_receive_control_stream.cc
+++ b/quic/core/http/quic_receive_control_stream.cc
@@ -123,7 +123,8 @@
 QuicReceiveControlStream::QuicReceiveControlStream(PendingStream* pending)
     : QuicStream(pending, READ_UNIDIRECTIONAL, /*is_static=*/true),
       received_settings_length_(0),
-      http_decoder_visitor_(new HttpDecoderVisitor(this)) {
+      http_decoder_visitor_(new HttpDecoderVisitor(this)),
+      sequencer_offset_(sequencer()->NumBytesConsumed()) {
   decoder_.set_visitor(http_decoder_visitor_.get());
   sequencer()->set_level_triggered(true);
 }
@@ -141,10 +142,16 @@
 
 void QuicReceiveControlStream::OnDataAvailable() {
   iovec iov;
-  while (!reading_stopped() && decoder_.error() == QUIC_NO_ERROR &&
-         sequencer()->PrefetchNextRegion(&iov)) {
-    decoder_.ProcessInput(reinterpret_cast<const char*>(iov.iov_base),
-                          iov.iov_len);
+  while (!reading_stopped() && decoder_.error() == QUIC_NO_ERROR) {
+    DCHECK_GE(sequencer_offset_, sequencer()->NumBytesConsumed());
+    if (!sequencer()->PeekRegion(sequencer_offset_, &iov)) {
+      break;
+    }
+
+    DCHECK(!sequencer()->IsClosed());
+    QuicByteCount processed_bytes = decoder_.ProcessInput(
+        reinterpret_cast<const char*>(iov.iov_base), iov.iov_len);
+    sequencer_offset_ += processed_bytes;
   }
 }
 
diff --git a/quic/core/http/quic_receive_control_stream.h b/quic/core/http/quic_receive_control_stream.h
index 79964ba..e4e9c20 100644
--- a/quic/core/http/quic_receive_control_stream.h
+++ b/quic/core/http/quic_receive_control_stream.h
@@ -46,6 +46,12 @@
 
   // HttpDecoder's visitor.
   std::unique_ptr<HttpDecoderVisitor> http_decoder_visitor_;
+
+  // Sequencer offset keeping track of how much data HttpDecoder has processed.
+  // Initial value is sequencer()->NumBytesConsumed() at time of
+  // QuicReceiveControlStream construction: that is the length of the
+  // unidirectional stream type at the beginning of the stream.
+  QuicStreamOffset sequencer_offset_;
 };
 
 }  // namespace quic
diff --git a/quic/core/http/quic_spdy_stream.cc b/quic/core/http/quic_spdy_stream.cc
index 6db96fa..f02eaeb 100644
--- a/quic/core/http/quic_spdy_stream.cc
+++ b/quic/core/http/quic_spdy_stream.cc
@@ -171,9 +171,12 @@
       headers_bytes_to_be_marked_consumed_(0),
       http_decoder_visitor_(new HttpDecoderVisitor(this)),
       body_buffer_(sequencer()),
+      sequencer_offset_(0),
+      is_decoder_processing_input_(false),
       ack_listener_(nullptr) {
   DCHECK(!QuicUtils::IsCryptoStreamId(
       spdy_session->connection()->transport_version(), id));
+  DCHECK_EQ(0u, sequencer()->NumBytesConsumed());
   // If headers are sent on the headers stream, then do not receive any
   // callbacks from the sequencer until headers are complete.
   if (!VersionUsesQpack(spdy_session_->connection()->transport_version())) {
@@ -202,6 +205,8 @@
       headers_bytes_to_be_marked_consumed_(0),
       http_decoder_visitor_(new HttpDecoderVisitor(this)),
       body_buffer_(sequencer()),
+      sequencer_offset_(sequencer()->NumBytesConsumed()),
+      is_decoder_processing_input_(false),
       ack_listener_(nullptr) {
   DCHECK(!QuicUtils::IsCryptoStreamId(
       spdy_session->connection()->transport_version(), id()));
@@ -621,12 +626,24 @@
     return;
   }
 
+  if (is_decoder_processing_input_) {
+    // Let the outermost nested OnDataAvailable() call do the work.
+    return;
+  }
+
   iovec iov;
-  while (!reading_stopped() && decoder_.error() == QUIC_NO_ERROR &&
-         sequencer()->PrefetchNextRegion(&iov)) {
+  while (!reading_stopped() && decoder_.error() == QUIC_NO_ERROR) {
+    DCHECK_GE(sequencer_offset_, sequencer()->NumBytesConsumed());
+    if (!sequencer()->PeekRegion(sequencer_offset_, &iov)) {
+      break;
+    }
+
     DCHECK(!sequencer()->IsClosed());
-    decoder_.ProcessInput(reinterpret_cast<const char*>(iov.iov_base),
-                          iov.iov_len);
+    is_decoder_processing_input_ = true;
+    QuicByteCount processed_bytes = decoder_.ProcessInput(
+        reinterpret_cast<const char*>(iov.iov_base), iov.iov_len);
+    is_decoder_processing_input_ = false;
+    sequencer_offset_ += processed_bytes;
   }
 
   // Do not call OnBodyAvailable() until headers are consumed.
diff --git a/quic/core/http/quic_spdy_stream.h b/quic/core/http/quic_spdy_stream.h
index 57f2fe0..b6b46fe 100644
--- a/quic/core/http/quic_spdy_stream.h
+++ b/quic/core/http/quic_spdy_stream.h
@@ -291,6 +291,16 @@
   // Buffer that contains decoded data of the stream.
   QuicSpdyStreamBodyBuffer body_buffer_;
 
+  // Sequencer offset keeping track of how much data HttpDecoder has processed.
+  // Initial value is zero for fresh streams, or sequencer()->NumBytesConsumed()
+  // at time of construction if a PendingStream is converted to account for the
+  // length of the unidirectional stream type at the beginning of the stream.
+  QuicStreamOffset sequencer_offset_;
+
+  // True when inside an HttpDecoder::ProcessInput() call.
+  // Used for detecting reentrancy.
+  bool is_decoder_processing_input_;
+
   // Ack listener of this stream, and it is notified when any of written bytes
   // are acked or retransmitted.
   QuicReferenceCountedPointer<QuicAckListenerInterface> ack_listener_;