diff --git a/tools/bundler.js b/tools/bundler.js
index a8bafb7f97..c719710f8a 100644
--- a/tools/bundler.js
+++ b/tools/bundler.js
@@ -1427,11 +1427,10 @@ _.extend(ServerTarget.prototype, {
       'os.linux.x86_64': 'Linux_x86_64',
       'os.osx.x86_64': 'Darwin_x86_64'
     };
-    var arch = archinfo.host();
-    var platform = archToPlatform[arch];
+    var platform = archToPlatform[self.arch];
     if (! platform) {
       buildmessage.error("MDG does not publish dev_bundles for arch: " +
-                         arch);
+                         self.arch);
       // Recover by bailing out and leaving a partially built target
       return;
     }
@@ -1661,6 +1660,7 @@ var writeSiteArchive = function (targets, outputPath, options) {
  *   - minify: minify the CSS and JS assets (boolean, default false)
  *   - testPackages: array of package objects or package names whose
  *     tests should be additionally included in this bundle
+ *   - arch: the server architecture to target (defaults to archinfo.host())
  *
  * Returns an object with keys:
  * - errors: A buildmessage.MessageSet, or falsy if bundling succeeded.
@@ -1737,7 +1737,7 @@ exports.bundle = function (options) {
     var makeServerTarget = function (app, clientTarget) {
       var targetOptions = {
         library: library,
-        arch: archinfo.host(),
+        arch: buildOptions.arch || archinfo.host(),
         releaseName: releaseName
       };
       if (clientTarget)
@@ -2005,6 +2005,11 @@ exports.buildJsImage = function (options) {
 
   var target = new JsImageTarget({
     library: options.library,
+    // This function does not yet support cross-compilation (neither does
+    // initFromOptions). That's OK for now since we're only trying to support
+    // cross-bundling, not cross-package-building, and this function is only
+    // used to build plugins (during package build) and for unipackage.load
+    // (which always wants to build for the current host).
     arch: archinfo.host()
   });
   target.make({ packages: [pkg] });
diff --git a/tools/commands.js b/tools/commands.js
index fa67c49f35..d4e99876b6 100644
--- a/tools/commands.js
+++ b/tools/commands.js
@@ -62,6 +62,8 @@ var getPackages = function () {
   return null;
 };
 
+var XXX_DEPLOY_ARCH = 'os.linux.x86_64';
+
 ///////////////////////////////////////////////////////////////////////////////
 // options that act like commands
 ///////////////////////////////////////////////////////////////////////////////
@@ -640,7 +642,9 @@ constraint.packageName + "@" + constraint.versionConstraint  + ": no such versio
         // system. (Later we may also need to download more builds to be able to
         // deploy to another architecture.)
         var available = tropohouse.maybeDownloadPackageForArchitectures(
-          versionInfo, ['browser', archinfo.host()]);
+          // XXX we also download the deploy arch now, because we don't run the
+          // constraint solver / downloader anywhere other than add-package yet.
+          versionInfo, ['browser', archinfo.host(), XXX_DEPLOY_ARCH]);
         if (! available) {
           // XXX maybe we shouldn't be letting the constraint solver choose
           // things that don't have the right arches?
@@ -778,7 +782,8 @@ main.registerCommand({
     outputPath: bundlePath,
     nodeModulesMode: options['for-deploy'] ? 'skip' : 'copy',
     buildOptions: {
-      minify: ! options.debug
+      minify: ! options.debug,
+      arch: XXX_DEPLOY_ARCH  // XXX should do this in deploy instead but it's easier to test with bundle
     }
   });
   if (bundleResult.errors) {
diff --git a/tools/packages.js b/tools/packages.js
index 9a3b15d693..e6c5d4bcf0 100644
--- a/tools/packages.js
+++ b/tools/packages.js
@@ -1229,10 +1229,10 @@ _.extend(Package.prototype, {
     self.sources = _.uniq(self.sources);
   },
 
-  // Programmatically initialized a package from scratch. For now,
-  // cannot create browser packages. This function does not retrieve
-  // the package's dependencies from the library, and on return,
-  // the package will be in an unbuilt state.
+  // Programmatically initialized a package from scratch. For now, cannot create
+  // browser packages or cross-targeted packages (eg os.linux when host is
+  // os.osx). This function does not retrieve the package's dependencies from
+  // the library, and on return, the package will be in an unbuilt state.
   //
   // Unlike user-facing methods of creating a package
   // (initFromPackageDir, initFromAppDir) this does not implicitly add