diff --git a/app/ghcup/Main.hs b/app/ghcup/Main.hs
index 5f0941a..b4eac9a 100644
--- a/app/ghcup/Main.hs
+++ b/app/ghcup/Main.hs
@@ -213,6 +213,8 @@ data HLSCompileOptions = HLSCompileOptions
   , ovewrwiteVer :: Maybe Version
   , isolateDir   :: Maybe FilePath
   , cabalProject :: Maybe FilePath
+  , cabalProjectLocal :: Maybe FilePath
+  , patchDir     :: Maybe FilePath
   , targetGHCs   :: [ToolVersion]
   }
 
@@ -1268,8 +1270,22 @@ hlsCompileOpts =
     <*> optional
           (option
             str
-            (short 'p' <> long "projectfile" <> metavar "CABAL_PROJECT_LOCAL" <> help
-              "Absolute path to a cabal.project.local to be used for the build"
+            (long "cabal-project" <> metavar "CABAL_PROJECT" <> help
+              "If relative, specifies the path to cabal.project inside the unpacked HLS tarball/checkout. If absolute, will copy the file over."
+            )
+          )
+    <*> optional
+          (option
+            (eitherReader absolutePathParser)
+            (long "cabal-project-local" <> metavar "CABAL_PROJECT_LOCAL" <> help
+              "Absolute path to a cabal.project.local to be used for the build. Will be copied over."
+            )
+          )
+    <*> optional
+          (option
+            (eitherReader absolutePathParser)
+            (short 'p' <> long "patchdir" <> metavar "PATCH_DIR" <> help
+              "Absolute path to patch directory (applies all .patch and .diff files in order using -p1)"
             )
           )
     <*> some (toolVersionArgument Nothing (Just GHC))
@@ -1504,6 +1520,11 @@ isolateParser f = case isValid f of
               True -> Right $ normalise f
               False -> Left "Please enter a valid filepath for isolate dir."
 
+absolutePathParser :: FilePath -> Either String FilePath
+absolutePathParser f = case isValid f && isAbsolute f of
+              True -> Right $ normalise f
+              False -> Left "Please enter a valid absolute filepath."
+
 toSettings :: Options -> IO (Settings, KeyBindings)
 toSettings options = do
   userConf <- runE @'[ JSONError ] ghcupConfigFile >>= \case
@@ -2357,6 +2378,8 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                             ovewrwiteVer
                             isolateDir
                             cabalProject
+                            cabalProjectLocal
+                            patchDir
                 GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
                 let vi = getVersionInfo targetVer HLS dls
                 when setCompile $ void $ liftE $
diff --git a/lib/GHCup.hs b/lib/GHCup.hs
index 5b25a09..502d86e 100644
--- a/lib/GHCup.hs
+++ b/lib/GHCup.hs
@@ -754,6 +754,8 @@ compileHLS :: ( MonadMask m
            -> Maybe Version
            -> Maybe FilePath
            -> Maybe FilePath
+           -> Maybe FilePath
+           -> Maybe FilePath
            -> Excepts '[ NoDownload
                        , GPGError
                        , DownloadFailed
@@ -764,7 +766,7 @@ compileHLS :: ( MonadMask m
                        , BuildFailed
                        , NotInstalled
                        ] m Version
-compileHLS targetHLS ghcs jobs ov isolateDir cabalProject = do
+compileHLS targetHLS ghcs jobs ov isolateDir cabalProject cabalProjectLocal patchdir = do
   PlatformRequest { .. } <- lift getPlatformReq
   GHCupInfo { _ghcupDownloads = dls } <- lift getGHCupInfo
   Dirs { .. } <- lift getDirs
@@ -835,13 +837,26 @@ compileHLS targetHLS ghcs jobs ov isolateDir cabalProject = do
   liftE $ runBuildAction
     workdir
     Nothing
-    (reThrowAll @_ @'[ProcessError, FileAlreadyExistsError, CopyError] @'[BuildFailed] (BuildFailed workdir) $ do
+    (reThrowAll @_ @'[PatchFailed, ProcessError, FileAlreadyExistsError, CopyError] @'[BuildFailed] (BuildFailed workdir) $ do
       let installDir = workdir </> "out"
+      liftIO $ createDirRecursive' installDir
+
+      -- apply patches
+      forM_ patchdir (\dir -> liftE $ applyPatches dir workdir)
+
+      -- set up project files
+      cp <- case cabalProject of
+        Just cp
+          | isAbsolute cp -> do
+              handleIO (throwE . CopyError . show) $ liftIO $ copyFile cp (workdir </> "cabal.project")
+              pure "cabal.project"
+          | otherwise -> pure (takeFileName cp)
+        Nothing -> pure "cabal.project"
+      forM_ cabalProjectLocal $ \cpl -> handleIO (throwE . CopyError . show) $ liftIO $ copyFile cpl (workdir </> cp <.> "local")
 
       artifacts <- forM (sort ghcs) $ \ghc -> do
         let ghcInstallDir = installDir </> T.unpack (prettyVer ghc)
         liftIO $ createDirRecursive' installDir
-        forM_ cabalProject $ \cp -> handleIO (throwE . CopyError . show) $ liftIO $ copyFile cp (workdir </> "cabal.project.local")
         lift $ logInfo $ "Building HLS " <> prettyVer installVer <> " for GHC version " <> prettyVer ghc
         liftE $ lEM @_ @'[ProcessError] $
           execLogged "cabal" ( [ "v2-install"
@@ -857,6 +872,7 @@ compileHLS targetHLS ghcs jobs ov isolateDir cabalProject = do
                                , "--enable-executable-stripping"
                                , "--enable-executable-static"
                                , "--installdir=" <> ghcInstallDir
+                               , "--project-file=" <> cp
                                , "exe:haskell-language-server"
                                , "exe:haskell-language-server-wrapper"]
                              )