diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index 74aa4a1..c4fc7e6 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -77,6 +77,8 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_enable_server_on_wire_ping, true)
 // If true, ignore peer_max_ack_delay during handshake.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_ignore_peer_max_ack_delay_during_handshake, false)
+// If true, include non-default port in the origin field of the ACCEPT_CH frame in ALPS.
+QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_include_port_in_alps_origin, false)
 // If true, include stream information in idle timeout connection close detail.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_add_stream_info_to_idle_close_detail, true)
 // If true, increase the size of stream sequencer buffer block container on demand.
diff --git a/quic/core/tls_server_handshaker.cc b/quic/core/tls_server_handshaker.cc
index 65b9c3a..96dc4bf 100644
--- a/quic/core/tls_server_handshaker.cc
+++ b/quic/core/tls_server_handshaker.cc
@@ -34,6 +34,13 @@
 
 namespace quic {
 
+namespace {
+
+// Default port for HTTP/3.
+uint16_t kDefaultPort = 443;
+
+}  // namespace
+
 TlsServerHandshaker::DefaultProofSourceHandle::DefaultProofSourceHandle(
     TlsServerHandshaker* handshaker,
     ProofSource* proof_source)
@@ -1015,6 +1022,15 @@
   const std::string& hostname = crypto_negotiated_params_->sni;
   std::string accept_ch_value = GetAcceptChValueForHostname(hostname);
   std::string origin = absl::StrCat("https://", hostname);
+  if (GetQuicReloadableFlag(quic_include_port_in_alps_origin)) {
+    QUIC_RELOADABLE_FLAG_COUNT(quic_include_port_in_alps_origin);
+    uint16_t port = session()->self_address().port();
+    if (port != kDefaultPort) {
+      // This should be rare in production, but useful for test servers.
+      QUIC_CODE_COUNT(quic_server_alps_non_default_port);
+      absl::StrAppend(&origin, ":", port);
+    }
+  }
 
   if (!accept_ch_value.empty()) {
     AcceptChFrame frame{{{std::move(origin), std::move(accept_ch_value)}}};