diff --git a/src/net/spdy/spdy_proxy_client_socket.cc b/src/net/spdy/spdy_proxy_client_socket.cc
index 9ac5064025..804ef7ba72 100644
--- a/src/net/spdy/spdy_proxy_client_socket.cc
+++ b/src/net/spdy/spdy_proxy_client_socket.cc
@@ -373,6 +373,20 @@ int SpdyProxyClientSocket::DoLoop(int last_io_result) {
       case STATE_PROCESS_RESPONSE_CODE:
         DCHECK_EQ(OK, rv);
         rv = DoProcessResponseCode();
+        if (use_fastopen_ && read_headers_pending_) {
+          read_headers_pending_ = false;
+          if (rv < 0) {
+            // read_callback_ cannot be called.
+            if (!read_callback_)
+              rv = ERR_IO_PENDING;
+            // read_callback_ will be called with this error and be reset.
+            // Further data after that will be ignored.
+            next_state_ = STATE_DISCONNECTED;
+          } else {
+            // Does not call read_callback_ from here if headers are OK.
+            rv = ERR_IO_PENDING;
+          }
+        }
         break;
       default:
         NOTREACHED() << "bad state";
@@ -434,6 +448,10 @@ int SpdyProxyClientSocket::DoCalculateHeadersComplete(int result) {
     return result;
   }
   next_state_ = STATE_SEND_REQUEST;
+  if (proxy_delegate_headers_.HasHeader("fastopen")) {
+    proxy_delegate_headers_.RemoveHeader("fastopen");
+    use_fastopen_ = true;
+  }
   request_.extra_headers.MergeFrom(proxy_delegate_headers_);
   return result;
 }
@@ -461,6 +479,12 @@ int SpdyProxyClientSocket::DoSendRequestComplete(int result) {
   if (result < 0)
     return result;
 
+  if (use_fastopen_) {
+    read_headers_pending_ = true;
+    next_state_ = STATE_OPEN;
+    return OK;
+  }
+
   // Wait for HEADERS frame from the server
   next_state_ = STATE_READ_REPLY_COMPLETE;
   return ERR_IO_PENDING;
@@ -541,6 +565,10 @@ void SpdyProxyClientSocket::OnEarlyHintsReceived(
 
 void SpdyProxyClientSocket::OnHeadersReceived(
     const quiche::HttpHeaderBlock& response_headers) {
+  if (use_fastopen_ && read_headers_pending_ && next_state_ == STATE_OPEN) {
+    next_state_ = STATE_READ_REPLY_COMPLETE;
+  }
+
   // If we've already received the reply, existing headers are too late.
   // TODO(mbelshe): figure out a way to make HEADERS frames useful after the
   //                initial response.
diff --git a/src/net/spdy/spdy_proxy_client_socket.h b/src/net/spdy/spdy_proxy_client_socket.h
index e5e2353914..aca80e455b 100644
--- a/src/net/spdy/spdy_proxy_client_socket.h
+++ b/src/net/spdy/spdy_proxy_client_socket.h
@@ -200,6 +200,9 @@ class NET_EXPORT_PRIVATE SpdyProxyClientSocket : public ProxyClientSocket,
   // True if the transport socket has ever sent data.
   bool was_ever_used_ = false;
 
+  bool use_fastopen_ = false;
+  bool read_headers_pending_ = false;
+
   const NetLogWithSource net_log_;
   const NetLogSource source_dependency_;