diff --git a/python/mozbuild/mozbuild/html_build_viewer.py b/python/mozbuild/mozbuild/html_build_viewer.py
index 619f79569bb8..5151f04a4824 100644
--- a/python/mozbuild/mozbuild/html_build_viewer.py
+++ b/python/mozbuild/mozbuild/html_build_viewer.py
@@ -10,6 +10,8 @@ import BaseHTTPServer
 import json
 import os
 
+import requests
+
 
 class HTTPHandler(BaseHTTPServer.BaseHTTPRequestHandler):
     def do_GET(self):
@@ -36,9 +38,7 @@ class HTTPHandler(BaseHTTPServer.BaseHTTPRequestHandler):
             self.send_header('Content-Type', 'application/json; charset=utf-8')
             self.end_headers()
 
-            with open(s.json_files[key], 'rb') as fh:
-                self.wfile.write(fh.read())
-
+            self.wfile.write(s.json_files[key])
             return
 
         if p == '/':
@@ -105,7 +105,15 @@ class BuildViewerServer(object):
         """Register a resource JSON file with the server.
 
         The file will be made available under the name/key specified."""
-        self.json_files[key] = path
+        with open(path, 'rb') as fh:
+            self.json_files[key] = fh.read()
+
+    def add_resource_json_url(self, key, url):
+        """Register a resource JSON file at a URL."""
+        r = requests.get(url)
+        if r.status_code != 200:
+            raise Exception('Non-200 HTTP response code')
+        self.json_files[key] = r.text
 
     def run(self):
         while not self.do_shutdown:
diff --git a/python/mozbuild/mozbuild/mach_commands.py b/python/mozbuild/mozbuild/mach_commands.py
index aeeb5aa42f43..a2cb8db61945 100644
--- a/python/mozbuild/mozbuild/mach_commands.py
+++ b/python/mozbuild/mozbuild/mach_commands.py
@@ -579,19 +579,25 @@ class Build(MachCommandBase):
         help='Port number the HTTP server should listen on.')
     @CommandArgument('--browser', default='firefox',
         help='Web browser to automatically open. See webbrowser Python module.')
-    def resource_usage(self, address=None, port=None, browser=None):
+    @CommandArgument('--url',
+        help='URL of JSON document to display')
+    def resource_usage(self, address=None, port=None, browser=None, url=None):
         import webbrowser
         from mozbuild.html_build_viewer import BuildViewerServer
 
-        last = self._get_state_filename('build_resources.json')
-        if not os.path.exists(last):
-            print('Build resources not available. If you have performed a '
-                'build and receive this message, the psutil Python package '
-                'likely failed to initialize properly.')
-            return 1
-
         server = BuildViewerServer(address, port)
-        server.add_resource_json_file('last', last)
+
+        if url:
+            server.add_resource_json_url('url', url)
+        else:
+            last = self._get_state_filename('build_resources.json')
+            if not os.path.exists(last):
+                print('Build resources not available. If you have performed a '
+                    'build and receive this message, the psutil Python package '
+                    'likely failed to initialize properly.')
+                return 1
+
+            server.add_resource_json_file('last', last)
         try:
             webbrowser.get(browser).open_new_tab(server.url)
         except Exception: