diff --git a/doc/sources/nghttpx-howto.rst b/doc/sources/nghttpx-howto.rst
index 813da5eb..e81ea70f 100644
--- a/doc/sources/nghttpx-howto.rst
+++ b/doc/sources/nghttpx-howto.rst
@@ -198,8 +198,8 @@ backend connection, use ``--backend-no-tls`` option.
 
 The backend server is supporsed to be a HTTP/2 web server or HTTP/2
 proxy.  If backend server is HTTP/2 proxy, use
-``--no-location-rewrite`` option to disable rewriting location header
-field.
+``--no-location-rewrite`` and ``--no-host-rewrite`` options to disable
+rewriting location, host and :authority header field.
 
 The use-case of this mode is aggregate the incoming connections to one
 HTTP/2 connection.  One backend HTTP/2 connection is created per
diff --git a/integration-tests/nghttpx_http1_test.go b/integration-tests/nghttpx_http1_test.go
index 48ac9f7c..d035f081 100644
--- a/integration-tests/nghttpx_http1_test.go
+++ b/integration-tests/nghttpx_http1_test.go
@@ -139,6 +139,78 @@ func TestH1H1GracefulShutdown(t *testing.T) {
 	}
 }
 
+// TestH1H1HostRewrite tests that server rewrites Host header field
+func TestH1H1HostRewrite(t *testing.T) {
+	st := newServerTester(nil, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("request-host", r.Host)
+	})
+	defer st.Close()
+
+	res, err := st.http1(requestParam{
+		name: "TestH1H1HostRewrite",
+	})
+	if err != nil {
+		t.Fatalf("Error st.http1() = %v", err)
+	}
+	if got, want := res.status, 200; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+	if got, want := res.header.Get("request-host"), st.backendHost; got != want {
+		t.Errorf("request-host: %v; want %v", got, want)
+	}
+}
+
+// TestH1H1HTTP10 tests that server can accept HTTP/1.0 request
+// without Host header field
+func TestH1H1HTTP10(t *testing.T) {
+	st := newServerTester(nil, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("request-host", r.Host)
+	})
+	defer st.Close()
+
+	if _, err := io.WriteString(st.conn, "GET / HTTP/1.0\r\nTest-Case: TestH1H1HTTP10\r\n\r\n"); err != nil {
+		t.Fatalf("Error io.WriteString() = %v", err)
+	}
+
+	resp, err := http.ReadResponse(bufio.NewReader(st.conn), nil)
+	if err != nil {
+		t.Fatalf("Error http.ReadResponse() = %v", err)
+	}
+
+	if got, want := resp.StatusCode, 200; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+	if got, want := resp.Header.Get("request-host"), st.backendHost; got != want {
+		t.Errorf("request-host: %v; want %v", got, want)
+	}
+}
+
+// TestH1H1HTTP10NoHostRewrite tests that server generates host header
+// field using actual backend server even if --no-http-rewrite is
+// used.
+func TestH1H1HTTP10NoHostRewrite(t *testing.T) {
+	st := newServerTester([]string{"--no-host-rewrite"}, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("request-host", r.Host)
+	})
+	defer st.Close()
+
+	if _, err := io.WriteString(st.conn, "GET / HTTP/1.0\r\nTest-Case: TestH1H1HTTP10NoHostRewrite\r\n\r\n"); err != nil {
+		t.Fatalf("Error io.WriteString() = %v", err)
+	}
+
+	resp, err := http.ReadResponse(bufio.NewReader(st.conn), nil)
+	if err != nil {
+		t.Fatalf("Error http.ReadResponse() = %v", err)
+	}
+
+	if got, want := resp.StatusCode, 200; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+	if got, want := resp.Header.Get("request-host"), st.backendHost; got != want {
+		t.Errorf("request-host: %v; want %v", got, want)
+	}
+}
+
 // TestH1H2ConnectFailure tests that server handles the situation that
 // connection attempt to HTTP/2 backend failed.
 func TestH1H2ConnectFailure(t *testing.T) {
@@ -184,6 +256,57 @@ func TestH1H2NoHost(t *testing.T) {
 	}
 }
 
+// TestH1H2HTTP10 tests that server can accept HTTP/1.0 request
+// without Host header field
+func TestH1H2HTTP10(t *testing.T) {
+	st := newServerTester([]string{"--http2-bridge"}, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("request-host", r.Host)
+	})
+	defer st.Close()
+
+	if _, err := io.WriteString(st.conn, "GET / HTTP/1.0\r\nTest-Case: TestH1H2HTTP10\r\n\r\n"); err != nil {
+		t.Fatalf("Error io.WriteString() = %v", err)
+	}
+
+	resp, err := http.ReadResponse(bufio.NewReader(st.conn), nil)
+	if err != nil {
+		t.Fatalf("Error http.ReadResponse() = %v", err)
+	}
+
+	if got, want := resp.StatusCode, 200; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+	if got, want := resp.Header.Get("request-host"), st.backendHost; got != want {
+		t.Errorf("request-host: %v; want %v", got, want)
+	}
+}
+
+// TestH1H2HTTP10NoHostRewrite tests that server generates host header
+// field using actual backend server even if --no-http-rewrite is
+// used.
+func TestH1H2HTTP10NoHostRewrite(t *testing.T) {
+	st := newServerTester([]string{"--http2-bridge", "--no-host-rewrite"}, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("request-host", r.Host)
+	})
+	defer st.Close()
+
+	if _, err := io.WriteString(st.conn, "GET / HTTP/1.0\r\nTest-Case: TestH1H2HTTP10NoHostRewrite\r\n\r\n"); err != nil {
+		t.Fatalf("Error io.WriteString() = %v", err)
+	}
+
+	resp, err := http.ReadResponse(bufio.NewReader(st.conn), nil)
+	if err != nil {
+		t.Fatalf("Error http.ReadResponse() = %v", err)
+	}
+
+	if got, want := resp.StatusCode, 200; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+	if got, want := resp.Header.Get("request-host"), st.backendHost; got != want {
+		t.Errorf("request-host: %v; want %v", got, want)
+	}
+}
+
 // TestH1H2CrumbleCookie tests that Cookies are crumbled and assembled
 // when forwarding to HTTP/2 backend link.  go-nghttp2 server
 // concatenates crumbled Cookies automatically, so this test is not
diff --git a/integration-tests/nghttpx_http2_test.go b/integration-tests/nghttpx_http2_test.go
index 6efe9859..3e24c912 100644
--- a/integration-tests/nghttpx_http2_test.go
+++ b/integration-tests/nghttpx_http2_test.go
@@ -192,6 +192,49 @@ func TestH2H1NoVia(t *testing.T) {
 	}
 }
 
+// TestH2H1HostRewrite tests that server rewrites host header field
+func TestH2H1HostRewrite(t *testing.T) {
+	st := newServerTester(nil, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("request-host", r.Host)
+	})
+	defer st.Close()
+
+	res, err := st.http2(requestParam{
+		name: "TestH2H1HostRewrite",
+	})
+	if err != nil {
+		t.Fatalf("Error st.http2() = %v", err)
+	}
+	if got, want := res.status, 200; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+	if got, want := res.header.Get("request-host"), st.backendHost; got != want {
+		t.Errorf("request-host: %v; want %v", got, want)
+	}
+}
+
+// TestH2H1NoHostRewrite tests that server does not rewrite host
+// header field
+func TestH2H1NoHostRewrite(t *testing.T) {
+	st := newServerTester([]string{"--no-host-rewrite"}, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("request-host", r.Host)
+	})
+	defer st.Close()
+
+	res, err := st.http2(requestParam{
+		name: "TestH2H1NoHostRewrite",
+	})
+	if err != nil {
+		t.Fatalf("Error st.http2() = %v", err)
+	}
+	if got, want := res.status, 200; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+	if got, want := res.header.Get("request-host"), st.frontendHost; got != want {
+		t.Errorf("request-host: %v; want %v", got, want)
+	}
+}
+
 // TestH2H1BadRequestCL tests that server rejects request whose
 // content-length header field value does not match its request body
 // size.
@@ -584,3 +627,46 @@ func TestH2H2ConnectFailure(t *testing.T) {
 		t.Errorf("status: %v; want %v", got, want)
 	}
 }
+
+// TestH2H2HostRewrite tests that server rewrites host header field
+func TestH2H2HostRewrite(t *testing.T) {
+	st := newServerTester([]string{"--http2-bridge"}, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("request-host", r.Host)
+	})
+	defer st.Close()
+
+	res, err := st.http2(requestParam{
+		name: "TestH2H2HostRewrite",
+	})
+	if err != nil {
+		t.Fatalf("Error st.http2() = %v", err)
+	}
+	if got, want := res.status, 200; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+	if got, want := res.header.Get("request-host"), st.backendHost; got != want {
+		t.Errorf("request-host: %v; want %v", got, want)
+	}
+}
+
+// TestH2H2NoHostRewrite tests that server does not rewrite host
+// header field
+func TestH2H2NoHostRewrite(t *testing.T) {
+	st := newServerTester([]string{"--http2-bridge", "--no-host-rewrite"}, t, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("request-host", r.Host)
+	})
+	defer st.Close()
+
+	res, err := st.http2(requestParam{
+		name: "TestH2H2NoHostRewrite",
+	})
+	if err != nil {
+		t.Fatalf("Error st.http2() = %v", err)
+	}
+	if got, want := res.status, 200; got != want {
+		t.Errorf("status: %v; want %v", got, want)
+	}
+	if got, want := res.header.Get("request-host"), st.frontendHost; got != want {
+		t.Errorf("request-host: %v; want %v", got, want)
+	}
+}
diff --git a/integration-tests/server_tester.go b/integration-tests/server_tester.go
index d323925a..93f421eb 100644
--- a/integration-tests/server_tester.go
+++ b/integration-tests/server_tester.go
@@ -42,6 +42,8 @@ type serverTester struct {
 	url           string    // test frontend server URL
 	t             *testing.T
 	ts            *httptest.Server // backend server
+	frontendHost  string           // frontend server host
+	backendHost   string           // backend server host
 	conn          net.Conn         // connection to frontend server
 	h2PrefaceSent bool             // HTTP/2 preface was sent in conn
 	nextStreamID  uint32           // next stream ID
@@ -124,6 +126,8 @@ func newServerTesterInternal(args []string, t *testing.T, handler http.HandlerFu
 		t:            t,
 		ts:           ts,
 		url:          fmt.Sprintf("%v://%v", scheme, authority),
+		frontendHost: fmt.Sprintf("127.0.0.1:%v", serverPort),
+		backendHost:  backendURL.Host,
 		nextStreamID: 1,
 		authority:    authority,
 		frCh:         make(chan http2.Frame),
diff --git a/src/http2.cc b/src/http2.cc
index 9ddf9bfb..ab9fc772 100644
--- a/src/http2.cc
+++ b/src/http2.cc
@@ -224,6 +224,7 @@ void copy_headers_to_nva(std::vector<nghttp2_nv> &nva, const Headers &headers) {
     switch (lookup_token(kv.name)) {
     case HD_COOKIE:
     case HD_CONNECTION:
+    case HD_HOST:
     case HD_HTTP2_SETTINGS:
     case HD_KEEP_ALIVE:
     case HD_PROXY_CONNECTION:
@@ -249,6 +250,7 @@ void build_http1_headers_from_headers(std::string &hdrs,
     switch (lookup_token(kv.name)) {
     case HD_CONNECTION:
     case HD_COOKIE:
+    case HD_HOST:
     case HD_HTTP2_SETTINGS:
     case HD_KEEP_ALIVE:
     case HD_PROXY_CONNECTION:
diff --git a/src/shrpx.cc b/src/shrpx.cc
index 2a418a61..933ab074 100644
--- a/src/shrpx.cc
+++ b/src/shrpx.cc
@@ -766,6 +766,7 @@ void fill_default_config() {
 
   mod_config()->tls_proto_mask = 0;
   mod_config()->no_location_rewrite = false;
+  mod_config()->no_host_rewrite = false;
   mod_config()->argc = 0;
   mod_config()->argv = nullptr;
   mod_config()->downstream_connections_per_host = 8;
@@ -1168,6 +1169,11 @@ HTTP:
               --client  and  default   mode.   For  --http2-proxy  and
               --client-proxy mode,  location header field will  not be
               altered regardless of this option.
+  --no-host-rewrite
+              Don't  rewrite  host  and :authority  header  fields  on
+              --http2-bridge,   --client   and  default   mode.    For
+              --http2-proxy  and  --client-proxy mode,  these  headers
+              will not be altered regardless of this option.
   --altsvc=<PROTOID,PORT[,HOST,[ORIGIN]]>
               Specify   protocol  ID,   port,  host   and  origin   of
               alternative service.  <HOST>  and <ORIGIN> are optional.
@@ -1332,6 +1338,7 @@ int main(int argc, char **argv) {
         {"tls-ctx-per-worker", no_argument, &flag, 70},
         {"backend-response-buffer", required_argument, &flag, 71},
         {"backend-request-buffer", required_argument, &flag, 72},
+        {"no-host-rewrite", no_argument, &flag, 73},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -1661,6 +1668,10 @@ int main(int argc, char **argv) {
         // --backend-request-buffer
         cmdcfgs.emplace_back(SHRPX_OPT_BACKEND_REQUEST_BUFFER, optarg);
         break;
+      case 73:
+        // --no-host-rewrite
+        cmdcfgs.emplace_back(SHRPX_OPT_NO_HOST_REWRITE, "yes");
+        break;
       default:
         break;
       }
diff --git a/src/shrpx_config.cc b/src/shrpx_config.cc
index a00184fa..f7e5c220 100644
--- a/src/shrpx_config.cc
+++ b/src/shrpx_config.cc
@@ -133,6 +133,7 @@ const char SHRPX_OPT_ADD_RESPONSE_HEADER[] = "add-response-header";
 const char SHRPX_OPT_WORKER_FRONTEND_CONNECTIONS[] =
     "worker-frontend-connections";
 const char SHRPX_OPT_NO_LOCATION_REWRITE[] = "no-location-rewrite";
+const char SHRPX_OPT_NO_HOST_REWRITE[] = "no-host-rewrite";
 const char SHRPX_OPT_BACKEND_HTTP1_CONNECTIONS_PER_HOST[] =
     "backend-http1-connections-per-host";
 const char SHRPX_OPT_BACKEND_HTTP1_CONNECTIONS_PER_FRONTEND[] =
@@ -1079,6 +1080,12 @@ int parse_config(const char *opt, const char *optarg) {
     return 0;
   }
 
+  if (util::strieq(opt, SHRPX_OPT_NO_HOST_REWRITE)) {
+    mod_config()->no_host_rewrite = util::strieq(optarg, "yes");
+
+    return 0;
+  }
+
   if (util::strieq(opt, SHRPX_OPT_BACKEND_HTTP1_CONNECTIONS_PER_HOST)) {
     int n;
 
diff --git a/src/shrpx_config.h b/src/shrpx_config.h
index 71b195cb..4f0a811f 100644
--- a/src/shrpx_config.h
+++ b/src/shrpx_config.h
@@ -123,6 +123,7 @@ extern const char SHRPX_OPT_ALTSVC[];
 extern const char SHRPX_OPT_ADD_RESPONSE_HEADER[];
 extern const char SHRPX_OPT_WORKER_FRONTEND_CONNECTIONS[];
 extern const char SHRPX_OPT_NO_LOCATION_REWRITE[];
+extern const char SHRPX_OPT_NO_HOST_REWRITE[];
 extern const char SHRPX_OPT_BACKEND_HTTP1_CONNECTIONS_PER_HOST[];
 extern const char SHRPX_OPT_BACKEND_HTTP1_CONNECTIONS_PER_FRONTEND[];
 extern const char SHRPX_OPT_LISTENER_DISABLE_TIMEOUT[];
@@ -299,6 +300,7 @@ struct Config {
   bool http2_no_cookie_crumbling;
   bool upstream_frame_debug;
   bool no_location_rewrite;
+  bool no_host_rewrite;
   bool auto_tls_ticket_key;
   bool tls_ctx_per_worker;
 };
diff --git a/src/shrpx_http2_downstream_connection.cc b/src/shrpx_http2_downstream_connection.cc
index 72f8645c..6b2b17a2 100644
--- a/src/shrpx_http2_downstream_connection.cc
+++ b/src/shrpx_http2_downstream_connection.cc
@@ -232,6 +232,34 @@ int Http2DownstreamConnection::push_request_headers() {
   if (!downstream_) {
     return 0;
   }
+
+  const char *authority = nullptr, *host = nullptr;
+  if (!get_config()->no_host_rewrite && !get_config()->http2_proxy &&
+      !get_config()->client_proxy) {
+    // HTTP/2 backend does not support multiple address, so we always
+    // use index = 0.
+    if (!downstream_->get_request_http2_authority().empty()) {
+      authority = get_config()->downstream_addrs[0].hostport.get();
+    }
+    if (downstream_->get_request_header(http2::HD_HOST)) {
+      host = get_config()->downstream_addrs[0].hostport.get();
+    }
+  } else {
+    if (!downstream_->get_request_http2_authority().empty()) {
+      authority = downstream_->get_request_http2_authority().c_str();
+    }
+    auto h = downstream_->get_request_header(http2::HD_HOST);
+    if (h) {
+      host = h->value.c_str();
+    }
+  }
+
+  if (!authority && !host) {
+    // upstream is HTTP/1.0.  We use backend server's host
+    // nonetheless.
+    host = get_config()->downstream_addrs[0].hostport.get();
+  }
+
   size_t nheader = downstream_->get_request_headers().size();
 
   Headers cookies;
@@ -239,28 +267,28 @@ int Http2DownstreamConnection::push_request_headers() {
     cookies = downstream_->crumble_request_cookie();
   }
 
-  // 7 means:
+  // 8 means:
   // 1. :method
   // 2. :scheme
   // 3. :path
-  // 4. :authority (optional)
-  // 5. via (optional)
-  // 6. x-forwarded-for (optional)
-  // 7. x-forwarded-proto (optional)
+  // 4. :authority (at least either :authority or host exists)
+  // 5. host
+  // 6. via (optional)
+  // 7. x-forwarded-for (optional)
+  // 8. x-forwarded-proto (optional)
   auto nva = std::vector<nghttp2_nv>();
-  nva.reserve(nheader + 7 + cookies.size());
+  nva.reserve(nheader + 8 + cookies.size());
 
   std::string via_value;
   std::string xff_value;
-  std::string scheme, authority, path, query;
+  std::string scheme, uri_authority, path, query;
 
   // To reconstruct HTTP/1 status line and headers, proxy should
   // preserve host header field. See draft-09 section 8.1.3.1.
   if (downstream_->get_request_method() == "CONNECT") {
     // The upstream may be HTTP/2 or HTTP/1
-    if (!downstream_->get_request_http2_authority().empty()) {
-      nva.push_back(http2::make_nv_ls(
-          ":authority", downstream_->get_request_http2_authority()));
+    if (authority) {
+      nva.push_back(http2::make_nv_lc(":authority", authority));
     } else {
       nva.push_back(
           http2::make_nv_ls(":authority", downstream_->get_request_path()));
@@ -270,14 +298,8 @@ int Http2DownstreamConnection::push_request_headers() {
     nva.push_back(
         http2::make_nv_ls(":scheme", downstream_->get_request_http2_scheme()));
     nva.push_back(http2::make_nv_ls(":path", downstream_->get_request_path()));
-    if (!downstream_->get_request_http2_authority().empty()) {
-      nva.push_back(http2::make_nv_ls(
-          ":authority", downstream_->get_request_http2_authority()));
-    } else if (!downstream_->get_request_header(http2::HD_HOST)) {
-      if (LOG_ENABLED(INFO)) {
-        DCLOG(INFO, this) << "host header field missing";
-      }
-      return -1;
+    if (authority) {
+      nva.push_back(http2::make_nv_lc(":authority", authority));
     }
   } else {
     // The upstream is HTTP/1
@@ -288,11 +310,11 @@ int Http2DownstreamConnection::push_request_headers() {
                                &u);
     if (rv == 0) {
       http2::copy_url_component(scheme, &u, UF_SCHEMA, url);
-      http2::copy_url_component(authority, &u, UF_HOST, url);
+      http2::copy_url_component(uri_authority, &u, UF_HOST, url);
       http2::copy_url_component(path, &u, UF_PATH, url);
       http2::copy_url_component(query, &u, UF_QUERY, url);
       if (path.empty()) {
-        if (!authority.empty() &&
+        if (!uri_authority.empty() &&
             downstream_->get_request_method() == "OPTIONS") {
           path = "*";
         } else {
@@ -319,28 +341,33 @@ int Http2DownstreamConnection::push_request_headers() {
     } else {
       nva.push_back(http2::make_nv_ls(":path", path));
     }
-    if (!authority.empty()) {
+
+    if (!get_config()->no_host_rewrite && !get_config()->http2_proxy &&
+        !get_config()->client_proxy) {
+      if (authority) {
+        nva.push_back(http2::make_nv_lc(":authority", authority));
+      }
+    } else if (!uri_authority.empty()) {
       // TODO properly check IPv6 numeric address
-      if (authority.find(":") != std::string::npos) {
-        authority = "[" + authority;
-        authority += "]";
+      if (uri_authority.find(":") != std::string::npos) {
+        uri_authority = "[" + uri_authority;
+        uri_authority += "]";
       }
       if (u.field_set & (1 << UF_PORT)) {
-        authority += ":";
-        authority += util::utos(u.port);
+        uri_authority += ":";
+        uri_authority += util::utos(u.port);
       }
-      nva.push_back(http2::make_nv_ls(":authority", authority));
-    } else if (!downstream_->get_request_header(http2::HD_HOST)) {
-      if (LOG_ENABLED(INFO)) {
-        DCLOG(INFO, this) << "host header field missing";
-      }
-      return -1;
+      nva.push_back(http2::make_nv_ls(":authority", uri_authority));
     }
   }
 
   nva.push_back(
       http2::make_nv_ls(":method", downstream_->get_request_method()));
 
+  if (host) {
+    nva.push_back(http2::make_nv_lc("host", host));
+  }
+
   http2::copy_headers_to_nva(nva, downstream_->get_request_headers());
 
   bool chunked_encoding = false;
diff --git a/src/shrpx_http2_session.cc b/src/shrpx_http2_session.cc
index 2a0f19c1..f421fc00 100644
--- a/src/shrpx_http2_session.cc
+++ b/src/shrpx_http2_session.cc
@@ -634,7 +634,8 @@ int on_stream_close_callback(nghttp2_session *session, int32_t stream_id,
   auto http2session = static_cast<Http2Session *>(user_data);
   if (LOG_ENABLED(INFO)) {
     SSLOG(INFO, http2session) << "Stream stream_id=" << stream_id
-                              << " is being closed";
+                              << " is being closed with error code "
+                              << error_code;
   }
   auto sd = static_cast<StreamData *>(
       nghttp2_session_get_stream_user_data(session, stream_id));
diff --git a/src/shrpx_http_downstream_connection.cc b/src/shrpx_http_downstream_connection.cc
index 3c6e87eb..559e898f 100644
--- a/src/shrpx_http_downstream_connection.cc
+++ b/src/shrpx_http_downstream_connection.cc
@@ -107,7 +107,7 @@ void connectcb(struct ev_loop *loop, ev_io *w, int revents) {
 HttpDownstreamConnection::HttpDownstreamConnection(
     DownstreamConnectionPool *dconn_pool, struct ev_loop *loop)
     : DownstreamConnection(dconn_pool), rlimit_(loop, &rev_, 0, 0),
-      ioctrl_(&rlimit_), response_htp_{0}, loop_(loop), fd_(-1) {
+      ioctrl_(&rlimit_), response_htp_{0}, loop_(loop), addr_idx_(0), fd_(-1) {
   // We do not know fd yet, so just set dummy fd 0
   ev_io_init(&wev_, connectcb, 0, EV_WRITE);
   ev_io_init(&rev_, readcb, 0, EV_READ);
@@ -198,6 +198,8 @@ int HttpDownstreamConnection::attach_downstream(Downstream *downstream) {
         DCLOG(INFO, this) << "Connecting to downstream server";
       }
 
+      addr_idx_ = i;
+
       ev_io_set(&wev_, fd_, EV_WRITE);
       ev_io_set(&rev_, fd_, EV_READ);
 
@@ -223,27 +225,51 @@ int HttpDownstreamConnection::attach_downstream(Downstream *downstream) {
 }
 
 int HttpDownstreamConnection::push_request_headers() {
+  const char *authority = nullptr, *host = nullptr;
+  if (!get_config()->no_host_rewrite && !get_config()->http2_proxy &&
+      !get_config()->client_proxy) {
+    if (!downstream_->get_request_http2_authority().empty()) {
+      authority = get_config()->downstream_addrs[addr_idx_].hostport.get();
+    }
+    if (downstream_->get_request_header(http2::HD_HOST)) {
+      host = get_config()->downstream_addrs[addr_idx_].hostport.get();
+    }
+  } else {
+    if (!downstream_->get_request_http2_authority().empty()) {
+      authority = downstream_->get_request_http2_authority().c_str();
+    }
+    auto h = downstream_->get_request_header(http2::HD_HOST);
+    if (h) {
+      host = h->value.c_str();
+    }
+  }
+
+  if (!authority && !host) {
+    // upstream is HTTP/1.0.  We use backend server's host
+    // nonetheless.
+    host = get_config()->downstream_addrs[addr_idx_].hostport.get();
+  }
+
   downstream_->assemble_request_cookie();
 
   // Assume that method and request path do not contain \r\n.
   std::string hdrs = downstream_->get_request_method();
   hdrs += " ";
   if (downstream_->get_request_method() == "CONNECT") {
-    if (!downstream_->get_request_http2_authority().empty()) {
-      hdrs += downstream_->get_request_http2_authority();
+    if (authority) {
+      hdrs += authority;
     } else {
       hdrs += downstream_->get_request_path();
     }
   } else if (get_config()->http2_proxy &&
-             !downstream_->get_request_http2_scheme().empty() &&
-             !downstream_->get_request_http2_authority().empty() &&
+             !downstream_->get_request_http2_scheme().empty() && authority &&
              (downstream_->get_request_path().c_str()[0] == '/' ||
               downstream_->get_request_path() == "*")) {
     // Construct absolute-form request target because we are going to
     // send a request to a HTTP/1 proxy.
     hdrs += downstream_->get_request_http2_scheme();
     hdrs += "://";
-    hdrs += downstream_->get_request_http2_authority();
+    hdrs += authority;
 
     // Server-wide OPTIONS takes following form in proxy request:
     //
@@ -259,13 +285,14 @@ int HttpDownstreamConnection::push_request_headers() {
     // don't care.
     hdrs += downstream_->get_request_path();
   }
-  hdrs += " HTTP/1.1\r\n";
-  if (!downstream_->get_request_header(http2::HD_HOST) &&
-      !downstream_->get_request_http2_authority().empty()) {
-    hdrs += "Host: ";
-    hdrs += downstream_->get_request_http2_authority();
-    hdrs += "\r\n";
+  hdrs += " HTTP/1.1\r\nHost: ";
+  if (authority) {
+    hdrs += authority;
+  } else {
+    hdrs += host;
   }
+  hdrs += "\r\n";
+
   http2::build_http1_headers_from_headers(hdrs,
                                           downstream_->get_request_headers());
 
diff --git a/src/shrpx_http_downstream_connection.h b/src/shrpx_http_downstream_connection.h
index d61de22b..fb95848b 100644
--- a/src/shrpx_http_downstream_connection.h
+++ b/src/shrpx_http_downstream_connection.h
@@ -70,6 +70,8 @@ private:
   IOControl ioctrl_;
   http_parser response_htp_;
   struct ev_loop *loop_;
+  // index of get_config()->downstream_addrs this object is using
+  size_t addr_idx_;
   int fd_;
 };
 
diff --git a/src/shrpx_https_upstream.cc b/src/shrpx_https_upstream.cc
index e2d5b2eb..32d64c8b 100644
--- a/src/shrpx_https_upstream.cc
+++ b/src/shrpx_https_upstream.cc
@@ -160,7 +160,11 @@ int htp_hdrs_completecb(http_parser *htp) {
     return -1;
   }
 
-  downstream->inspect_http1_request();
+  if (downstream->get_request_major() == 1 &&
+      downstream->get_request_minor() == 1 &&
+      !downstream->get_request_header(http2::HD_HOST)) {
+    return -1;
+  }
 
   if (get_config()->client_proxy &&
       downstream->get_request_method() != "CONNECT") {