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-graph.cabal b/hls-graph.cabal
new file mode 100644
--- /dev/null
+++ b/hls-graph.cabal
@@ -0,0 +1,57 @@
+cabal-version: 2.4
+name:          hls-graph
+version:       1.3.0.0
+synopsis:      Haskell Language Server internal graph API
+description:
+  Please see the README on GitHub at <https://github.com/haskell/haskell-language-server#readme>
+
+homepage:      https://github.com/haskell/haskell-language-server#readme
+bug-reports:   https://github.com/haskell/haskell-language-server/issues
+license:       Apache-2.0
+license-file:  LICENSE
+author:        The Haskell IDE Team
+maintainer:    alan.zimm@gmail.com
+copyright:     The Haskell IDE Team
+category:      Development
+build-type:    Simple
+
+flag pedantic
+  description: Enable -Werror
+  default:     False
+  manual:      True
+
+source-repository head
+  type:     git
+  location: https://github.com/haskell/haskell-language-server
+
+library
+  exposed-modules:
+    Development.IDE.Graph
+    Development.IDE.Graph.Classes
+    Development.IDE.Graph.Database
+    Development.IDE.Graph.Rule
+
+  other-modules:
+    Development.IDE.Graph.Internal.Action
+    Development.IDE.Graph.Internal.Options
+    Development.IDE.Graph.Internal.Rules
+
+  hs-source-dirs:     src
+  build-depends:
+    , base >=4.12 && <5
+    , bytestring
+    , shake >= 0.19.4
+    , unordered-containers
+
+  ghc-options:
+    -Wall -Wredundant-constraints -Wno-name-shadowing
+    -Wno-unticked-promoted-constructors
+
+  if flag(pedantic)
+    ghc-options: -Werror
+
+  default-language:   Haskell2010
+  default-extensions:
+    DataKinds
+    KindSignatures
+    TypeOperators
diff --git a/src/Development/IDE/Graph.hs b/src/Development/IDE/Graph.hs
new file mode 100644
--- /dev/null
+++ b/src/Development/IDE/Graph.hs
@@ -0,0 +1,25 @@
+{-# LANGUAGE PatternSynonyms #-}
+
+module Development.IDE.Graph(
+    shakeOptions,
+    Rules,
+    Action, action,
+    actionFinally, actionBracket, actionCatch,
+    Shake.ShakeException(..),
+    -- * Configuration
+    ShakeOptions(shakeAllowRedefineRules, shakeThreads, shakeFiles, shakeExtra),
+    getShakeExtra, getShakeExtraRules, newShakeExtra,
+    -- * Explicit parallelism
+    parallel,
+    -- * Oracle rules
+    Shake.ShakeValue, Shake.RuleResult,
+    -- * Special rules
+    alwaysRerun,
+    -- * Batching
+    reschedule,
+    ) where
+
+import qualified Development.Shake as Shake
+import Development.IDE.Graph.Internal.Action
+import Development.IDE.Graph.Internal.Options
+import Development.IDE.Graph.Internal.Rules
diff --git a/src/Development/IDE/Graph/Classes.hs b/src/Development/IDE/Graph/Classes.hs
new file mode 100644
--- /dev/null
+++ b/src/Development/IDE/Graph/Classes.hs
@@ -0,0 +1,6 @@
+
+module Development.IDE.Graph.Classes(
+    Show(..), Typeable, Eq(..), Hashable(..), Binary(..), NFData(..)
+    ) where
+
+import Development.Shake.Classes
diff --git a/src/Development/IDE/Graph/Database.hs b/src/Development/IDE/Graph/Database.hs
new file mode 100644
--- /dev/null
+++ b/src/Development/IDE/Graph/Database.hs
@@ -0,0 +1,18 @@
+
+module Development.IDE.Graph.Database(
+    Shake.ShakeDatabase,
+    shakeOpenDatabase,
+    shakeRunDatabase,
+    Shake.shakeProfileDatabase,
+    ) where
+
+import qualified Development.Shake.Database as Shake
+import Development.IDE.Graph.Internal.Action
+import Development.IDE.Graph.Internal.Options
+import Development.IDE.Graph.Internal.Rules
+
+shakeOpenDatabase :: ShakeOptions -> Rules () -> IO (IO Shake.ShakeDatabase, IO ())
+shakeOpenDatabase a b = Shake.shakeOpenDatabase (fromShakeOptions a) (fromRules b)
+
+shakeRunDatabase :: Shake.ShakeDatabase -> [Action a] -> IO ([a], [IO ()])
+shakeRunDatabase a b = Shake.shakeRunDatabase a (map fromAction b)
diff --git a/src/Development/IDE/Graph/Internal/Action.hs b/src/Development/IDE/Graph/Internal/Action.hs
new file mode 100644
--- /dev/null
+++ b/src/Development/IDE/Graph/Internal/Action.hs
@@ -0,0 +1,38 @@
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE TypeFamilies #-}
+
+module Development.IDE.Graph.Internal.Action where
+
+import qualified Development.Shake as Shake
+import qualified Development.Shake.Rule as Shake
+import Development.Shake.Classes
+import Control.Exception
+import Control.Monad.IO.Class
+import Control.Monad.Fail
+
+newtype Action a = Action {fromAction :: Shake.Action a}
+    deriving (Monad, Applicative, Functor, MonadIO, MonadFail)
+
+alwaysRerun :: Action ()
+alwaysRerun = Action Shake.alwaysRerun
+
+reschedule :: Double -> Action ()
+reschedule = Action . Shake.reschedule
+
+parallel :: [Action a] -> Action [a]
+parallel = Action . Shake.parallel . map fromAction
+
+actionCatch :: Exception e => Action a -> (e -> Action a) -> Action a
+actionCatch a b = Action $ Shake.actionCatch (fromAction a) (fromAction . b)
+
+actionBracket :: IO a -> (a -> IO b) -> (a -> Action c) -> Action c
+actionBracket a b c = Action $ Shake.actionBracket a b (fromAction . c)
+
+actionFinally :: Action a -> IO b -> Action a
+actionFinally a b = Action $ Shake.actionFinally (fromAction a) b
+
+apply1 :: (Shake.RuleResult key ~ value, Shake.ShakeValue key, Typeable value) => key -> Action value
+apply1 = Action . Shake.apply1
+
+apply :: (Shake.RuleResult key ~ value, Shake.ShakeValue key, Typeable value) => [key] -> Action [value]
+apply = Action . Shake.apply
diff --git a/src/Development/IDE/Graph/Internal/Options.hs b/src/Development/IDE/Graph/Internal/Options.hs
new file mode 100644
--- /dev/null
+++ b/src/Development/IDE/Graph/Internal/Options.hs
@@ -0,0 +1,40 @@
+{-# LANGUAGE RecordWildCards #-}
+
+module Development.IDE.Graph.Internal.Options where
+
+import qualified Development.Shake as Shake
+import qualified Data.HashMap.Strict as Map
+import Development.IDE.Graph.Internal.Action
+import Development.IDE.Graph.Internal.Rules
+import Data.Dynamic
+
+data ShakeOptions = ShakeOptions {
+    shakeThreads :: Int,
+    shakeFiles :: FilePath,
+    shakeExtra :: Maybe Dynamic,
+    shakeAllowRedefineRules :: Bool,
+    shakeTimings :: Bool
+    }
+
+shakeOptions :: ShakeOptions
+shakeOptions = ShakeOptions 0 ".shake" Nothing False False
+
+fromShakeOptions :: ShakeOptions -> Shake.ShakeOptions
+fromShakeOptions ShakeOptions{..} = Shake.shakeOptions{
+    Shake.shakeThreads = shakeThreads,
+    Shake.shakeFiles = shakeFiles,
+    Shake.shakeExtra = maybe Map.empty f shakeExtra,
+    Shake.shakeAllowRedefineRules = shakeAllowRedefineRules,
+    Shake.shakeTimings = shakeTimings
+    }
+    where f x = Map.singleton (dynTypeRep x) x
+
+
+getShakeExtra :: Typeable a => Action (Maybe a)
+getShakeExtra = Action Shake.getShakeExtra
+
+getShakeExtraRules :: Typeable a => Rules (Maybe a)
+getShakeExtraRules = Rules Shake.getShakeExtraRules
+
+newShakeExtra :: Typeable a => a -> Maybe Dynamic
+newShakeExtra = Just . toDyn
diff --git a/src/Development/IDE/Graph/Internal/Rules.hs b/src/Development/IDE/Graph/Internal/Rules.hs
new file mode 100644
--- /dev/null
+++ b/src/Development/IDE/Graph/Internal/Rules.hs
@@ -0,0 +1,24 @@
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE TypeFamilies #-}
+
+module Development.IDE.Graph.Internal.Rules where
+
+import qualified Development.Shake as Shake
+import qualified Development.Shake.Rule as Shake
+import Development.Shake.Classes
+import Development.IDE.Graph.Internal.Action
+import Control.Monad.IO.Class
+import Control.Monad.Fail
+import qualified Data.ByteString as BS
+
+newtype Rules a = Rules {fromRules :: Shake.Rules a}
+    deriving (Monoid, Semigroup, Monad, Applicative, Functor, MonadIO, MonadFail)
+
+action :: Action a -> Rules ()
+action = Rules . Shake.action . fromAction
+
+addRule
+    :: (Shake.RuleResult key ~ value, Shake.ShakeValue key, Typeable value, NFData value, Show value)
+    => (key -> Maybe BS.ByteString -> Shake.RunMode -> Action (Shake.RunResult value))
+    -> Rules ()
+addRule f = Rules $ Shake.addBuiltinRule Shake.noLint Shake.noIdentity $ \k bs r -> fromAction $ f k bs r
diff --git a/src/Development/IDE/Graph/Rule.hs b/src/Development/IDE/Graph/Rule.hs
new file mode 100644
--- /dev/null
+++ b/src/Development/IDE/Graph/Rule.hs
@@ -0,0 +1,15 @@
+{-# LANGUAGE TypeFamilies #-}
+
+module Development.IDE.Graph.Rule(
+    -- * Defining builtin rules
+    -- | Functions and types for defining new types of Shake rules.
+    addRule,
+    Shake.RunMode(..), Shake.RunChanged(..), Shake.RunResult(..),
+    -- * Calling builtin rules
+    -- | Wrappers around calling Shake rules. In general these should be specialised to a builtin rule.
+    apply, apply1,
+    ) where
+
+import qualified Development.Shake.Rule as Shake
+import Development.IDE.Graph.Internal.Action
+import Development.IDE.Graph.Internal.Rules