diff --git a/.gitignore b/.gitignore
index 450f32ec..a4caccaf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,3 +18,4 @@ cabal.sandbox.config
 .stack-work/
 cabal.project.local
 .HTF/
+output/
diff --git a/grin/app/Main.hs b/grin/app/Main.hs
index ec400af5..8fff1d86 100644
--- a/grin/app/Main.hs
+++ b/grin/app/Main.hs
@@ -6,40 +6,44 @@ import System.Environment
 import Text.Printf
 import Text.PrettyPrint.ANSI.Leijen hiding ((<$>))
 
+import AbstractRunGrin
 import Eval
-import ParseGrin hiding (value)
 import Grin
+import ParseGrin hiding (value)
+import Pipeline
 import Pretty
 import PrettyHPT
-import Transformations
-import TrafoPlayground
-import AbstractRunGrin
-import qualified CodeGenX64 as CGX64
-import qualified CodeGenLLVM as CGLLVM
-import qualified JITLLVM
-import VarGen
 import System.Process
+import TrafoPlayground
+import Transformations
+import VarGen
+
+import qualified CodeGenLLVM as CGLLVM
+import qualified CodeGenX64 as CGX64
+import qualified JITLLVM
 
 import Data.IntMap as IntMap
 import Data.Map as Map
-import qualified Text.Show.Pretty as PS
 import LLVM.Pretty (ppllvm)
-import qualified Data.Text.Lazy.IO as Text
 import System.FilePath
 
-import Control.Monad.Trans.State.Strict
 import Control.Monad.IO.Class
-import Lens.Micro
-import Lens.Micro.TH
-import Lens.Micro.Mtl
+import Control.Monad.Trans.State.Strict
 import Data.Set
+import Lens.Micro
+import Lens.Micro.Mtl
+import Lens.Micro.TH
 import Options.Applicative
 
-import Pipeline
+import qualified Text.Show.Pretty as PS
+import qualified Data.Text.Lazy.IO as Text
+
+
 
 data Options = Options
-  { optFiles :: [FilePath]
-  , optTrans :: [Pipeline]
+  { optFiles     :: [FilePath]
+  , optTrans     :: [Pipeline]
+  , optOutputDir :: FilePath
   } deriving Show
 
 flg c l h = flag' c (mconcat [long l, help h])
@@ -88,11 +92,18 @@ options = execParser $ info
     pipelineArgs = Options
       <$> some (argument str (metavar "FILES..."))
       <*> many pipelineOpts
+      <*> strOption (mconcat
+            [ short 'o'
+            , long "output-dir"
+            , help "Output directory for generated files"
+            , value "./output"
+            ])
 
 defaultPipeline :: Options -> Options
 defaultPipeline = \case
-  Options files [] ->
-    Options files
+  Options files [] output ->
+    Options
+      files
       [ HPT
       , T CaseSimplification
       , T Vectorisation
@@ -104,11 +115,12 @@ defaultPipeline = \case
       , SaveLLVM "code"
       , JITLLVM
       ]
+      output
   opts -> opts
 
 main :: IO ()
 main = do
-  Options files steps <- defaultPipeline <$> options
+  Options files steps outputDir <- defaultPipeline <$> options
   forM_ files $ \fname -> do
     grin <- either (fail . show) id <$> parseGrin fname
     let program = Program grin
@@ -117,4 +129,5 @@ main = do
     putStrLn $ unlines result
     putStrLn "* tag info *"
     putStrLn . show . collectTagInfo $ program
-    pipeline program steps
+    let opts = PipelineOpts { _poOutputDir = outputDir }
+    pipeline opts program steps
diff --git a/grin/grin.cabal b/grin/grin.cabal
index cac05918..b2043b07 100644
--- a/grin/grin.cabal
+++ b/grin/grin.cabal
@@ -57,7 +57,8 @@ library
     process,
     text,
     llvm-hs-pretty,
-    optparse-applicative
+    optparse-applicative,
+    directory
   default-language:    Haskell2010
 
 executable grin
@@ -79,6 +80,7 @@ executable grin
                      , microlens-th
                      , microlens-mtl
                      , optparse-applicative
+                     , directory
   default-language:    Haskell2010
 
 test-suite grin-test
diff --git a/grin/src/Pipeline.hs b/grin/src/Pipeline.hs
index 08a9d734..9886a444 100644
--- a/grin/src/Pipeline.hs
+++ b/grin/src/Pipeline.hs
@@ -3,7 +3,7 @@ module Pipeline where
 
 import Control.Monad
 import Text.Printf
-import Text.PrettyPrint.ANSI.Leijen hiding ((<$>))
+import Text.PrettyPrint.ANSI.Leijen hiding ((<$>), (</>))
 
 import Eval
 import Grin
@@ -13,17 +13,20 @@ import TrafoPlayground
 import AbstractRunGrin
 import qualified CodeGenLLVM as CGLLVM
 import qualified JITLLVM
+import System.Directory
 import System.Process
 
 import Data.Map as Map
 import LLVM.Pretty (ppllvm)
 import qualified Data.Text.Lazy.IO as Text
 
+import Control.Monad.Trans.Reader
 import Control.Monad.Trans.State.Strict
 import Control.Monad.IO.Class
 import Lens.Micro.TH
 import Lens.Micro.Mtl
 import Data.Set
+import System.FilePath
 
 
 type RenameVariablesMap = Map String String
@@ -73,8 +76,12 @@ pattern PrintGrin :: (Doc -> Doc) -> Pipeline
 pattern PrintGrin c <- PrintGrinH (H c)
   where PrintGrin c =  PrintGrinH (H c)
 
+data PipelineOpts = PipelineOpts
+  { _poOutputDir :: FilePath
+  }
+
 type TagInfo = Set Tag
-type PipelineM a = StateT PState IO a
+type PipelineM a = ReaderT PipelineOpts (StateT PState IO) a
 data PState = PState
     { _psExp :: Exp
     , _psTransStep :: Int
@@ -83,6 +90,7 @@ data PState = PState
     }
 
 makeLenses ''PState
+makeLenses ''PipelineOpts
 
 pipelineStep :: Pipeline -> PipelineM ()
 pipelineStep = \case
@@ -135,13 +143,19 @@ saveGrin :: FilePath -> PipelineM ()
 saveGrin fn = do
   n <- use psTransStep
   e <- use psExp
-  liftIO . writeFile (concat [fn,".", show n]) . show $ pretty e
+  outputDir <- view poOutputDir
+  let fname = (concat [fn,".", show n])
+  let content = show $ pretty e
+  liftIO $ do
+    createDirectoryIfMissing True outputDir
+    writeFile (outputDir </> fname) content
 
 saveLLVM :: FilePath -> PipelineM ()
 saveLLVM fname' = do
   e <- use psExp
   n <- use psTransStep
-  let fname = concat [fname',".",show n]
+  o <- view poOutputDir
+  let fname = o </> concat [fname',".",show n]
       code = CGLLVM.codeGen e
       llName = printf "%s.ll" fname
       sName = printf "%s.s" fname
@@ -153,9 +167,9 @@ saveLLVM fname' = do
     callProcess "llc-5.0" [llName]
     readFile sName >>= putStrLn
 
-pipeline :: Exp -> [Pipeline] -> IO ()
-pipeline e p = do
+pipeline :: PipelineOpts -> Exp -> [Pipeline] -> IO ()
+pipeline o e p = do
   print p
-  flip evalStateT start . sequence_ $ Prelude.map pipelineStep p
+  flip evalStateT start . flip runReaderT o . sequence_ $ Prelude.map pipelineStep p
   where
     start = PState e 0 Nothing Nothing