diff --git a/lib/mix/lib/mix/tasks/format.ex b/lib/mix/lib/mix/tasks/format.ex
index 2951ceac1ac..0abd1be3585 100644
--- a/lib/mix/lib/mix/tasks/format.ex
+++ b/lib/mix/lib/mix/tasks/format.ex
@@ -703,19 +703,25 @@ defmodule Mix.Tasks.Format do
   defp find_formatter_for_file(file, formatter_opts) do
     ext = Path.extname(file)
 
+    base_formatter =
+      cond do
+        ext in ~w(.ex .exs) ->
+          &elixir_format(&1, [file: file] ++ formatter_opts)
+
+        true ->
+          & &1
+      end
+
     cond do
       plugins = find_plugins_for_extension(formatter_opts, ext) ->
         fn input ->
-          Enum.reduce(plugins, input, fn plugin, input ->
+          Enum.reduce(plugins, base_formatter.(input), fn plugin, input ->
             plugin.format(input, [extension: ext, file: file] ++ formatter_opts)
           end)
         end
 
-      ext in ~w(.ex .exs) ->
-        &elixir_format(&1, [file: file] ++ formatter_opts)
-
       true ->
-        & &1
+        base_formatter
     end
   end
 
diff --git a/lib/mix/test/mix/tasks/format_test.exs b/lib/mix/test/mix/tasks/format_test.exs
index f828e5c4790..fc6e4d5b00a 100644
--- a/lib/mix/test/mix/tasks/format_test.exs
+++ b/lib/mix/test/mix/tasks/format_test.exs
@@ -572,6 +572,125 @@ defmodule Mix.Tasks.FormatTest do
     end)
   end
 
+  defmodule Elixir.ExtensionExDoubleNewlinePlugin do
+    @behaviour Mix.Tasks.Format
+
+    def features(opts) do
+      assert opts[:from_formatter_exs] == :yes
+      [extensions: ~w(.ex .exs), sigils: []]
+    end
+
+    def format(contents, opts) do
+      assert opts[:from_formatter_exs] == :yes
+      assert opts[:extension] == ".ex"
+      assert opts[:file] =~ ~r/\/a\.ex$/
+      contents |> String.split("\n") |> Enum.join("\n\n")
+    end
+  end
+
+  defmodule Elixir.ExtensionExUpcasePlugin do
+    @behaviour Mix.Tasks.Format
+
+    def features(opts) do
+      assert opts[:from_formatter_exs] == :yes
+      [extensions: ~w(.ex .exs), sigils: []]
+    end
+
+    def format(contents, opts) do
+      assert opts[:from_formatter_exs] == :yes
+      assert opts[:extension] == ".ex"
+      assert opts[:file] =~ ~r/\/a\.ex$/
+      String.upcase(contents)
+    end
+  end
+
+  test "uses plugin from .formatter.exs which targets .ex files, after standard Elixir code formatting",
+       context do
+    in_tmp(context.test, fn ->
+      File.write!(".formatter.exs", """
+      [
+        inputs: ["a.ex"],
+        plugins: [ExtensionExUpcasePlugin],
+        from_formatter_exs: :yes
+      ]
+      """)
+
+      File.write!("a.ex", """
+      def   sigil_test( assigns  )  do
+        ~W"foo bar baz"abc
+      end
+      """)
+
+      Mix.Tasks.Format.run([])
+
+      assert File.read!("a.ex") == """
+             DEF SIGIL_TEST(ASSIGNS) DO
+               ~W"FOO BAR BAZ"ABC
+             END
+             """
+    end)
+  end
+
+  test "uses multiple plugins from .formatter.exs which target .ex files, after standard Elixir code formatting",
+       context do
+    in_tmp(context.test, fn ->
+      File.write!(".formatter.exs", """
+      [
+        inputs: ["a.ex"],
+        plugins: [ExtensionExDoubleNewlinePlugin, ExtensionExUpcasePlugin],
+        from_formatter_exs: :yes
+      ]
+      """)
+
+      File.write!("a.ex", """
+      def  sigil_test(assigns  )    do
+        ~W"foo bar baz"abc
+      end
+      """)
+
+      Mix.Tasks.Format.run([])
+
+      assert File.read!("a.ex") == """
+             DEF SIGIL_TEST(ASSIGNS) DO
+
+               ~W"FOO BAR BAZ"ABC
+
+             END
+
+             """
+    end)
+  end
+
+  test "uses multiple plugins from .formatter.exs which target both .ex files and sigils within them, after standard Elixir code formatting",
+       context do
+    in_tmp(context.test, fn ->
+      File.write!(".formatter.exs", """
+      [
+        inputs: ["a.ex"],
+        plugins: [ExtensionExDoubleNewlinePlugin, SigilWPlugin, NewlineToDotPlugin, ExtensionExUpcasePlugin],
+        from_formatter_exs: :yes
+      ]
+      """)
+
+      File.write!("a.ex", """
+      def sigil_test(   assigns)  do
+        ~W"foo bar baz"abc
+      end
+      """)
+
+      Mix.Tasks.Format.run([])
+
+      assert File.read!("a.ex") == """
+             DEF SIGIL_TEST(ASSIGNS) DO
+
+               ~W"FOO.BAR.BAZ"ABC
+
+             END
+
+             """
+    end)
+  end
+
   defmodule Elixir.SigilOuterPlugin do
     @behaviour Mix.Tasks.Format