diff --git a/lib/elixir/lib/code/formatter.ex b/lib/elixir/lib/code/formatter.ex
index 635d41f8968..7c0dd8bda31 100644
--- a/lib/elixir/lib/code/formatter.ex
+++ b/lib/elixir/lib/code/formatter.ex
@@ -181,7 +181,7 @@ defmodule Code.Formatter do
 
     sigils =
       Map.new(sigils, fn {key, value} ->
-        with true <- is_atom(key) and is_function(value, 1),
+        with true <- is_atom(key) and is_function(value, 2),
              [char] <- Atom.to_charlist(key),
              true <- char in ?A..?Z do
           {char, value}
@@ -189,7 +189,7 @@ defmodule Code.Formatter do
           _ ->
             raise ArgumentError,
                   ":sigils must be a keyword list with a single uppercased letter as key and an " <>
-                    "anonymous function expecting a single argument as value, got: #{inspect(sigils)}"
+                    "anonymous function expecting two arguments as value, got: #{inspect(sigils)}"
         end
       end)
 
@@ -1320,7 +1320,7 @@ defmodule Code.Formatter do
       entries =
         case state.sigils do
           %{^name => callback} ->
-            case callback.(hd(entries)) do
+            case callback.(hd(entries), sigil: List.to_atom([name]), modifiers: modifiers) do
               binary when is_binary(binary) ->
                 [binary]
 
diff --git a/lib/elixir/test/elixir/code_formatter/general_test.exs b/lib/elixir/test/elixir/code_formatter/general_test.exs
index 9559087fbac..5aed5d17cec 100644
--- a/lib/elixir/test/elixir/code_formatter/general_test.exs
+++ b/lib/elixir/test/elixir/code_formatter/general_test.exs
@@ -125,7 +125,11 @@ defmodule Code.Formatter.GeneralTest do
       ~W/foo bar baz/
       """
 
-      formatter = &(&1 |> String.split(~r/ +/) |> Enum.join(" "))
+      formatter = fn content, opts ->
+        assert opts == [sigil: :W, modifiers: []]
+        content |> String.split(~r/ +/) |> Enum.join(" ")
+      end
+
       assert_format bad, good, sigils: [W: formatter]
 
       bad = """
@@ -136,7 +140,11 @@ defmodule Code.Formatter.GeneralTest do
       var = ~W/foo bar baz/abc
       """
 
-      formatter = &(&1 |> String.split(~r/ +/) |> Enum.join(" "))
+      formatter = fn content, opts ->
+        assert opts == [sigil: :W, modifiers: 'abc']
+        content |> String.split(~r/ +/) |> Enum.join(" ")
+      end
+
       assert_format bad, good, sigils: [W: formatter]
     end
 
@@ -153,7 +161,11 @@ defmodule Code.Formatter.GeneralTest do
       '''
       """
 
-      formatter = &(&1 |> String.split(~r/ +/) |> Enum.join(" "))
+      formatter = fn content, opts ->
+        assert opts == [sigil: :W, modifiers: []]
+        content |> String.split(~r/ +/) |> Enum.join(" ")
+      end
+
       assert_format bad, good, sigils: [W: formatter]
 
       bad = """
@@ -176,7 +188,11 @@ defmodule Code.Formatter.GeneralTest do
       end
       """
 
-      formatter = &(&1 |> String.split(~r/ +/) |> Enum.join("\n"))
+      formatter = fn content, opts ->
+        assert opts == [sigil: :W, modifiers: 'abc']
+        content |> String.split(~r/ +/) |> Enum.join("\n")
+      end
+
       assert_format bad, good, sigils: [W: formatter]
     end
   end
diff --git a/lib/mix/lib/mix/tasks/format.ex b/lib/mix/lib/mix/tasks/format.ex
index 1fd5722ccae..b9e7f6c9a8b 100644
--- a/lib/mix/lib/mix/tasks/format.ex
+++ b/lib/mix/lib/mix/tasks/format.ex
@@ -102,6 +102,14 @@ defmodule Mix.Tasks.Format do
         end
       end
 
+  The `opts` passed to `format/2` contains all the formatting options and either:
+
+      * `:sigil` (atom) - the sigil being formatted, e.g. `:M`.
+
+      * `:modifiers` (charlist) - list of sigil modifiers.
+
+      * `:extension` (string) - the extension of the file being formatted, e.g. `".md"`.
+
   Now any application can use your formatter as follows:
 
       # .formatters.exs
@@ -490,7 +498,7 @@ defmodule Mix.Tasks.Format do
         &elixir_format(&1, [file: file] ++ formatter_opts)
 
       plugin = find_plugin_for_extension(formatter_opts, ext) ->
-        &plugin.format(&1, formatter_opts)
+        &plugin.format(&1, [extension: ext] ++ formatter_opts)
 
       true ->
         & &1
@@ -531,7 +539,7 @@ defmodule Mix.Tasks.Format do
     sigils =
       for plugin <- Keyword.fetch!(formatter_opts, :plugins),
           sigil <- find_sigils_from_plugins(plugin, formatter_opts),
-          do: {sigil, &plugin.format(&1, formatter_opts)}
+          do: {sigil, &plugin.format(&1, &2 ++ formatter_opts)}
 
     IO.iodata_to_binary([Code.format_string!(content, [sigils: sigils] ++ formatter_opts), ?\n])
   end
diff --git a/lib/mix/test/mix/tasks/format_test.exs b/lib/mix/test/mix/tasks/format_test.exs
index aacb19f128f..6473cfd4a71 100644
--- a/lib/mix/test/mix/tasks/format_test.exs
+++ b/lib/mix/test/mix/tasks/format_test.exs
@@ -199,11 +199,13 @@ defmodule Mix.Tasks.FormatTest do
 
     def features(opts) do
       assert opts[:from_formatter_exs] == :yes
-      [sigils: [:W], extensions: ~w(.w)]
+      [sigils: [:W]]
     end
 
     def format(contents, opts) do
       assert opts[:from_formatter_exs] == :yes
+      assert opts[:sigil] == :W
+      assert opts[:modifiers] == 'abc'
       contents |> String.split(~r/\s/) |> Enum.join("\n")
     end
   end
@@ -240,12 +242,27 @@ defmodule Mix.Tasks.FormatTest do
     end)
   end
 
+  defmodule Elixir.ExtensionWPlugin do
+    @behaviour Mix.Tasks.Format
+
+    def features(opts) do
+      assert opts[:from_formatter_exs] == :yes
+      [extensions: ~w(.w)]
+    end
+
+    def format(contents, opts) do
+      assert opts[:from_formatter_exs] == :yes
+      assert opts[:extension] == ".w"
+      contents |> String.split(~r/\s/) |> Enum.join("\n")
+    end
+  end
+
   test "uses extension plugins from .formatter.exs", context do
     in_tmp(context.test, fn ->
       File.write!(".formatter.exs", """
       [
         inputs: ["a.w"],
-        plugins: [SigilWPlugin],
+        plugins: [ExtensionWPlugin],
         from_formatter_exs: :yes
       ]
       """)