diff --git a/brightray/browser/url_request_context_getter.cc b/brightray/browser/url_request_context_getter.cc
index 8c772c81dd92..6ca9297b415b 100644
--- a/brightray/browser/url_request_context_getter.cc
+++ b/brightray/browser/url_request_context_getter.cc
@@ -8,12 +8,14 @@
 
 #include "browser/network_delegate.h"
 
+#include "base/command_line.h"
 #include "base/strings/string_util.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/worker_pool.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/cookie_store_factory.h"
 #include "content/public/common/url_constants.h"
+#include "net/base/host_mapping_rules.h"
 #include "net/cert/cert_verifier.h"
 #include "net/cookies/cookie_monster.h"
 #include "net/http/http_auth_handler_factory.h"
@@ -40,6 +42,27 @@ using content::BrowserThread;
 
 namespace brightray {
 
+namespace {
+
+// Comma-separated list of rules that control how hostnames are mapped.
+//
+// For example:
+//    "MAP * 127.0.0.1" --> Forces all hostnames to be mapped to 127.0.0.1
+//    "MAP *.google.com proxy" --> Forces all google.com subdomains to be
+//                                 resolved to "proxy".
+//    "MAP test.com [::1]:77 --> Forces "test.com" to resolve to IPv6 loopback.
+//                               Will also force the port of the resulting
+//                               socket address to be 77.
+//    "MAP * baz, EXCLUDE www.google.com" --> Remaps everything to "baz",
+//                                            except for "www.google.com".
+//
+// These mappings apply to the endpoint host in a net::URLRequest (the TCP
+// connect and host resolver in a direct connection, and the CONNECT in an http
+// proxy connection, and the endpoint host in a SOCKS proxy connection).
+const char kHostRules[]                     = "host-rules";
+
+}  // namespace
+
 URLRequestContextGetter::URLRequestContextGetter(
     const base::FilePath& base_path,
     base::MessageLoop* io_loop,
@@ -73,6 +96,8 @@ net::HostResolver* URLRequestContextGetter::host_resolver() {
 net::URLRequestContext* URLRequestContextGetter::GetURLRequestContext() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
   if (!url_request_context_.get()) {
     url_request_context_.reset(new net::URLRequestContext());
     network_delegate_ = network_delegate_factory_.Run().Pass();
@@ -142,6 +167,13 @@ net::URLRequestContext* URLRequestContextGetter::GetURLRequestContext() {
         url_request_context_->http_server_properties();
     network_session_params.ignore_certificate_errors = false;
 
+    // --host-rules
+    if (command_line.HasSwitch(kHostRules)) {
+      host_mapping_rules_.reset(new net::HostMappingRules);
+      host_mapping_rules_->SetRulesFromString(command_line.GetSwitchValueASCII(kHostRules));
+      network_session_params.host_mapping_rules = host_mapping_rules_.get();
+    }
+
     // Give |storage_| ownership at the end in case it's |mapped_host_resolver|.
     storage_->set_host_resolver(host_resolver.Pass());
     network_session_params.host_resolver =
diff --git a/brightray/browser/url_request_context_getter.h b/brightray/browser/url_request_context_getter.h
index 716b7e00b75e..e179f4e15ec7 100644
--- a/brightray/browser/url_request_context_getter.h
+++ b/brightray/browser/url_request_context_getter.h
@@ -16,6 +16,7 @@ class MessageLoop;
 }
 
 namespace net {
+class HostMappingRules;
 class HostResolver;
 class ProxyConfigService;
 class URLRequestContextStorage;
@@ -59,6 +60,7 @@ class URLRequestContextGetter : public net::URLRequestContextGetter {
   scoped_ptr<NetworkDelegate> network_delegate_;
   scoped_ptr<net::URLRequestContextStorage> storage_;
   scoped_ptr<net::URLRequestContext> url_request_context_;
+  scoped_ptr<net::HostMappingRules> host_mapping_rules_;
   content::ProtocolHandlerMap protocol_handlers_;
   content::ProtocolHandlerScopedVector protocol_interceptors_;