diff --git a/lib/ex_doc.ex b/lib/ex_doc.ex
index 116d24230..102037f9e 100644
--- a/lib/ex_doc.ex
+++ b/lib/ex_doc.ex
@@ -29,19 +29,19 @@ defmodule ExDoc do
   # Helpers
 
   defp normalize_options(options) do
-    pattern = options[:source_url_pattern] || guess_url(options[:source_url])
+    pattern = options[:source_url_pattern] || guess_url(options[:source_url], options[:source_ref] || "master")
     Keyword.put(options, :source_url_pattern, pattern)
   end
 
-  defp guess_url(url = <<"https://github.com/", _ :: binary>>) do
-    append_slash(url) <> "blob/master/%{path}#L%{line}"
+  defp guess_url(url = <<"https://github.com/", _ :: binary>>, ref) do
+    append_slash(url) <> "blob/#{ref}/%{path}#L%{line}"
   end
 
-  defp guess_url(url = <<"https://bitbucket.org/", _ :: binary>>) do
-    append_slash(url) <> "src/master/%{path}?at=master#cl-%{line}"
+  defp guess_url(url = <<"https://bitbucket.org/", _ :: binary>>, ref) do
+    append_slash(url) <> "src/#{ref}/%{path}#cl-%{line}"
   end
 
-  defp guess_url(other) do
+  defp guess_url(other, _) do
     other
   end
 
diff --git a/lib/ex_doc/cli.ex b/lib/ex_doc/cli.ex
index 585b5967e..2d63deaed 100644
--- a/lib/ex_doc/cli.ex
+++ b/lib/ex_doc/cli.ex
@@ -33,6 +33,7 @@ defmodule ExDoc.CLI do
       -f, --formatter   Docs formatter to use, default: ExDoc.HTMLFormatter
       -r, --source-root Path to the source code root, default: .
       -u, --source-url  URL to the source code
+      --source-ref      Branch/commit/tag used for source link inference, default: master
       -m, --main        The main, entry-point module in docs
 
     ## Source linking
@@ -48,6 +49,14 @@ defmodule ExDoc.CLI do
 
         https://github.com/elixir-lang/dynamo/blob/master/%{path}#L%{line}
 
+    To specify a particular branch or commit, use the `--source-ref` option:
+
+        --source-url "https://github.com/elixir-lang/dynamo" --source-ref "v1.0"
+
+    will result in the following URL pattern:
+
+        https://github.com/elixir-lang/dynamo/blob/v1.0/%{path}#L%{line}
+
     """
     exit(1)
   end
diff --git a/lib/mix_docs.ex b/lib/mix_docs.ex
index e6e02c07f..1c72e5cb4 100644
--- a/lib/mix_docs.ex
+++ b/lib/mix_docs.ex
@@ -31,6 +31,9 @@ defmodule Mix.Tasks.Docs do
   * `:source_url_pattern` - public URL of the project.
     Derived from project's `:source_url` if not present.
 
+  * `:source_ref` - the branch/commit/tag used for source link inference.
+    Ignored if `:source_url_pattern` is provided. Defaults to _master_.
+
   * `:main` - main module of the project, will be shown on the starting page.
     Derived from project's `:app` if not present.