Set @path and @base_dir on the Layout per whether it's in the theme

lib/jekyll/convertible.rb

@@ -39,7 +39,7 @@ module Jekyll
       filename = File.join(base, name)
 
       begin
-        self.content = File.read(site.in_source_dir(base, name),
+        self.content = File.read(@path || site.in_source_dir(base, name),
                                  Utils.merged_file_read_opts(site, opts))
         if content =~ Document::YAML_FRONT_MATTER_REGEXP
           self.content = $POSTMATCH

lib/jekyll/layout.rb

@@ -29,7 +29,14 @@ module Jekyll
       @site = site
       @base = base
       @name = name
+
+      if site.theme && site.theme.layouts_path.eql?(base)
+        @base_dir = site.theme.root
+        @path = site.in_theme_dir(base, name)
+      else
+        @base_dir = site.source
         @path = site.in_source_dir(base, name)
+      end
 
       self.data = {}
 
@@ -51,7 +58,7 @@ module Jekyll
     # Returns a String path which represents the relative path
     #   from the site source to this layout
     def relative_path
-      @relative_path ||= Pathname.new(path).relative_path_from(Pathname.new(site.source)).to_s
+      @relative_path ||= Pathname.new(path).relative_path_from(Pathname.new(@base_dir)).to_s
     end
   end
 end

lib/jekyll/page.rb

@@ -40,6 +40,7 @@ module Jekyll
       @base = base
       @dir  = dir
       @name = name
+      @path = site.in_source_dir(base, dir, name)
 
       process(name)
       read_yaml(File.join(base, dir), name)

lib/jekyll/site.rb

@@ -373,6 +373,19 @@ module Jekyll
       end
     end
 
+    # Public: Prefix a given path with the theme directory.
+    #
+    # paths - (optional) path elements to a file or directory within the
+    #         theme directory
+    #
+    # Returns a path which is prefixed with the theme root directory.
+    def in_theme_dir(*paths)
+      return nil unless theme
+      paths.reduce(theme.root) do |base, path|
+        Jekyll.sanitized_path(base, path)
+      end
+    end
+
     # Public: Prefix a given path with the destination directory.
     #
     # paths - (optional) path elements to a file or directory within the