diff --git a/BUILD b/BUILD
index 7099a7ab..b9370c57 100644
--- a/BUILD
+++ b/BUILD
@@ -254,6 +254,7 @@ proto_library(
         "//envoy/extensions/stat_sinks/graphite_statsd/v3:pkg",
         "//envoy/extensions/stat_sinks/wasm/v3:pkg",
         "//envoy/extensions/transport_sockets/alts/v3:pkg",
+        "//envoy/extensions/transport_sockets/http_11_proxy/v3:pkg",
         "//envoy/extensions/transport_sockets/internal_upstream/v3:pkg",
         "//envoy/extensions/transport_sockets/proxy_protocol/v3:pkg",
         "//envoy/extensions/transport_sockets/quic/v3:pkg",
diff --git a/envoy/extensions/transport_sockets/http_11_proxy/v3/BUILD b/envoy/extensions/transport_sockets/http_11_proxy/v3/BUILD
new file mode 100644
index 00000000..1c1a6f6b
--- /dev/null
+++ b/envoy/extensions/transport_sockets/http_11_proxy/v3/BUILD
@@ -0,0 +1,12 @@
+# DO NOT EDIT. This file is generated by tools/proto_format/proto_sync.py.
+
+load("@envoy_api//bazel:api_build_system.bzl", "api_proto_package")
+
+licenses(["notice"])  # Apache 2
+
+api_proto_package(
+    deps = [
+        "//envoy/config/core/v3:pkg",
+        "@com_github_cncf_udpa//udpa/annotations:pkg",
+    ],
+)
diff --git a/envoy/extensions/transport_sockets/http_11_proxy/v3/upstream_http_11_connect.proto b/envoy/extensions/transport_sockets/http_11_proxy/v3/upstream_http_11_connect.proto
new file mode 100644
index 00000000..99c2e451
--- /dev/null
+++ b/envoy/extensions/transport_sockets/http_11_proxy/v3/upstream_http_11_connect.proto
@@ -0,0 +1,36 @@
+syntax = "proto3";
+
+package envoy.extensions.transport_sockets.http_11_proxy.v3;
+
+import "envoy/config/core/v3/base.proto";
+
+import "udpa/annotations/status.proto";
+import "validate/validate.proto";
+
+option java_package = "io.envoyproxy.envoy.extensions.transport_sockets.http_11_proxy.v3";
+option java_outer_classname = "UpstreamHttp11ConnectProto";
+option java_multiple_files = true;
+option go_package = "github.com/envoyproxy/go-control-plane/envoy/extensions/transport_sockets/http_11_proxy/v3;http_11_proxyv3";
+option (udpa.annotations.file_status).package_version_status = ACTIVE;
+
+// [#protodoc-title: Upstream HTTP/1.1 Proxy]
+// [#extension: envoy.transport_sockets.http_11_proxy]
+
+// Configuration for HTTP/1.1 proxy transport sockets.
+// This is intended for use in Envoy Mobile, though may eventually be extended
+// for upstream Envoy use.
+// If this transport socket is configured, and an intermediate filter adds the
+// stream info necessary for proxying to the stream info (as the test filter
+// does :repo:`here <test/integration/filters/header_to_proxy_filter.cc>`) then
+//
+// * Upstream connections will be directed to the specified proxy address rather
+//   than the host's address
+// * Upstream TLS connections will have a raw HTTP/1.1 CONNECT header prefaced
+//   to the payload, and 200 response stripped (if less than 200 bytes)
+// * Plaintext HTTP/1.1 connections will be sent with a fully qualified URL.
+//
+// This transport socket is not compatible with HTTP/3, plaintext HTTP/2, or raw TCP.
+message Http11ProxyUpstreamTransport {
+  // The underlying transport socket being wrapped.
+  config.core.v3.TransportSocket transport_socket = 1 [(validate.rules).message = {required: true}];
+}
diff --git a/versioning/BUILD b/versioning/BUILD
index da23a1e7..a873cfc2 100644
--- a/versioning/BUILD
+++ b/versioning/BUILD
@@ -196,6 +196,7 @@ proto_library(
         "//envoy/extensions/stat_sinks/graphite_statsd/v3:pkg",
         "//envoy/extensions/stat_sinks/wasm/v3:pkg",
         "//envoy/extensions/transport_sockets/alts/v3:pkg",
+        "//envoy/extensions/transport_sockets/http_11_proxy/v3:pkg",
         "//envoy/extensions/transport_sockets/internal_upstream/v3:pkg",
         "//envoy/extensions/transport_sockets/proxy_protocol/v3:pkg",
         "//envoy/extensions/transport_sockets/quic/v3:pkg",