diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,201 @@
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diff --git a/hls-ormolu-plugin.cabal b/hls-ormolu-plugin.cabal
new file mode 100644
--- /dev/null
+++ b/hls-ormolu-plugin.cabal
@@ -0,0 +1,47 @@
+cabal-version:      2.4
+name:               hls-ormolu-plugin
+version:            1.0.0.0
+synopsis:           Integration with the Ormolu code formatter
+description:
+  Please see the README on GitHub at <https://github.com/haskell/haskell-language-server#readme>
+
+license:            Apache-2.0
+license-file:       LICENSE
+author:             The Haskell IDE Team
+copyright:          The Haskell IDE Team
+maintainer:         alan.zimm@gmail.com
+category:           Development
+build-type:         Simple
+extra-source-files:
+  LICENSE
+  test/testdata/**/*.hs
+
+library
+  exposed-modules:  Ide.Plugin.Ormolu
+  hs-source-dirs:   src
+  build-depends:
+    , base            >=4.12  && <5
+    , filepath
+    , ghc
+    , ghc-boot-th
+    , ghcide          >=1.2   && <1.5
+    , hls-plugin-api  ^>=1.1
+    , lens
+    , lsp
+    , ormolu          ^>=0.1.2
+    , text
+
+  default-language: Haskell2010
+
+test-suite tests
+  type:             exitcode-stdio-1.0
+  default-language: Haskell2010
+  hs-source-dirs:   test
+  main-is:          Main.hs
+  ghc-options:      -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+    , base
+    , filepath
+    , hls-ormolu-plugin
+    , hls-test-utils     ^>=1.0
+    , lsp-types
diff --git a/src/Ide/Plugin/Ormolu.hs b/src/Ide/Plugin/Ormolu.hs
new file mode 100644
--- /dev/null
+++ b/src/Ide/Plugin/Ormolu.hs
@@ -0,0 +1,75 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeApplications  #-}
+
+module Ide.Plugin.Ormolu
+  ( descriptor
+  , provider
+  )
+where
+
+import           Control.Exception           (try)
+import           Control.Monad.IO.Class      (liftIO)
+import qualified Data.Text                   as T
+import           Development.IDE             hiding (pluginHandlers)
+import           Development.IDE.GHC.Compat  (moduleNameString)
+import qualified DynFlags                    as D
+import qualified EnumSet                     as S
+import           GHC.LanguageExtensions.Type
+import           GhcPlugins                  (HscEnv (hsc_dflags))
+import           Ide.PluginUtils
+import           Ide.Types
+import           Language.LSP.Server         hiding (defaultConfig)
+import           Language.LSP.Types
+import           Ormolu
+import           System.FilePath             (takeFileName)
+
+-- ---------------------------------------------------------------------
+
+descriptor :: PluginId -> PluginDescriptor IdeState
+descriptor plId = (defaultPluginDescriptor plId)
+  { pluginHandlers = mkFormattingHandlers provider
+  }
+
+-- ---------------------------------------------------------------------
+
+provider :: FormattingHandler IdeState
+provider ideState typ contents fp _ = withIndefiniteProgress title Cancellable $ liftIO $ do
+  ghc <- runAction "Ormolu" ideState $ use GhcSession fp
+  let df = hsc_dflags . hscEnv <$> ghc
+  fileOpts <- case df of
+    Nothing -> pure []
+    Just df -> pure $ fromDyn df
+
+  let
+    fullRegion = RegionIndices Nothing Nothing
+    rangeRegion s e = RegionIndices (Just $ s + 1) (Just $ e + 1)
+    mkConf o region = defaultConfig { cfgDynOptions = o, cfgRegion = region }
+    fmt :: T.Text -> Config RegionIndices -> IO (Either OrmoluException T.Text)
+    fmt cont conf =
+      try @OrmoluException $ ormolu conf (fromNormalizedFilePath fp) $ T.unpack cont
+
+  case typ of
+    FormatText -> ret <$> fmt contents (mkConf fileOpts fullRegion)
+    FormatRange (Range (Position sl _) (Position el _)) ->
+      ret <$> fmt contents (mkConf fileOpts (rangeRegion sl el))
+ where
+   title = T.pack $ "Formatting " <> takeFileName (fromNormalizedFilePath fp)
+
+   ret :: Either OrmoluException T.Text -> Either ResponseError (List TextEdit)
+   ret (Left err)  = Left . responseError . T.pack $ "ormoluCmd: " ++ show err
+   ret (Right new) = Right $ makeDiffTextEdit contents new
+
+   fromDyn :: D.DynFlags -> [DynOption]
+   fromDyn df =
+     let
+       pp =
+         let p = D.sPgm_F $ D.settings df
+         in  ["-pgmF=" <> p | not (null p)]
+       pm = ("-fplugin=" <>) . moduleNameString <$> D.pluginModNames df
+       ex = showExtension <$> S.toList (D.extensionFlags df)
+     in
+       DynOption <$> pp <> pm <> ex
+
+showExtension :: Extension -> String
+showExtension Cpp   = "-XCPP"
+showExtension other = "-X" ++ show other
diff --git a/test/Main.hs b/test/Main.hs
new file mode 100644
--- /dev/null
+++ b/test/Main.hs
@@ -0,0 +1,29 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Main
+  ( main
+  ) where
+
+import qualified Ide.Plugin.Ormolu  as Ormolu
+import           Language.LSP.Types
+import           System.FilePath
+import           Test.Hls
+
+main :: IO ()
+main = defaultTestRunner tests
+
+ormoluPlugin :: PluginDescriptor IdeState
+ormoluPlugin = Ormolu.descriptor "ormolu"
+
+tests :: TestTree
+tests = testGroup "ormolu"
+  [ goldenWithOrmolu "formats correctly" "Ormolu" "formatted" $ \doc -> do
+      formatDoc doc (FormattingOptions 4 True Nothing Nothing Nothing)
+  , goldenWithOrmolu "formats imports correctly" "Ormolu2" "formatted" $ \doc -> do
+      formatDoc doc (FormattingOptions 4 True Nothing Nothing Nothing)
+  ]
+
+goldenWithOrmolu :: TestName -> FilePath -> FilePath -> (TextDocumentIdentifier -> Session ()) -> TestTree
+goldenWithOrmolu title path desc = goldenWithHaskellDocFormatter ormoluPlugin "ormolu" title testDataDir path desc "hs"
+
+testDataDir :: FilePath
+testDataDir = "test" </> "testdata"
diff --git a/test/testdata/Ormolu.expected.hs b/test/testdata/Ormolu.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/Ormolu.expected.hs
@@ -0,0 +1,16 @@
+module Ormolu where
+
+import Data.Int
+import Data.List
+import Prelude
+
+foo :: Int -> Int
+foo 3 = 2
+foo x = x
+
+bar :: String -> IO String
+bar s = do
+  x <- return "hello"
+  return "asdf"
+
+data Baz = Baz {a :: Int, b :: String}
diff --git a/test/testdata/Ormolu.formatted.hs b/test/testdata/Ormolu.formatted.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/Ormolu.formatted.hs
@@ -0,0 +1,16 @@
+module Ormolu where
+
+import Data.Int
+import Data.List
+import Prelude
+
+foo :: Int -> Int
+foo 3 = 2
+foo x = x
+
+bar :: String -> IO String
+bar s = do
+  x <- return "hello"
+  return "asdf"
+
+data Baz = Baz {a :: Int, b :: String}
diff --git a/test/testdata/Ormolu.hs b/test/testdata/Ormolu.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/Ormolu.hs
@@ -0,0 +1,15 @@
+module    Ormolu where
+import Data.List
+
+import Prelude
+import Data.Int
+foo   :: Int ->  Int
+foo  3 = 2
+foo    x  = x
+bar   :: String ->   IO String
+bar s =  do
+      x <- return "hello"
+      return "asdf"
+
+data Baz = Baz { a :: Int, b :: String }
+
diff --git a/test/testdata/Ormolu2.expected.hs b/test/testdata/Ormolu2.expected.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/Ormolu2.expected.hs
@@ -0,0 +1,5 @@
+import Data.Bool
+import Data.Char
+import Data.Data
+import Data.Either
+import Data.Int
diff --git a/test/testdata/Ormolu2.formatted.hs b/test/testdata/Ormolu2.formatted.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/Ormolu2.formatted.hs
@@ -0,0 +1,5 @@
+import Data.Bool
+import Data.Char
+import Data.Data
+import Data.Either
+import Data.Int
diff --git a/test/testdata/Ormolu2.hs b/test/testdata/Ormolu2.hs
new file mode 100644
--- /dev/null
+++ b/test/testdata/Ormolu2.hs
@@ -0,0 +1,5 @@
+import Data.Char
+import Data.Either
+import Data.Int
+import Data.Data
+import Data.Bool
