diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 2.6
+
+* Atomic upsert support for postgreSQL backend
+
 ## 2.5
 
 * changes for read/write typeclass split
diff --git a/Database/Persist/Postgresql.hs b/Database/Persist/Postgresql.hs
--- a/Database/Persist/Postgresql.hs
+++ b/Database/Persist/Postgresql.hs
@@ -8,6 +8,7 @@
 {-# LANGUAGE DeriveDataTypeable #-}
 {-# LANGUAGE ViewPatterns #-}
 {-# LANGUAGE Rank2Types #-}
+{-# LANGUAGE DeriveDataTypeable #-}
 
 -- | A postgresql backend for persistent.
 module Database.Persist.Postgresql
@@ -44,7 +45,7 @@
 import Control.Exception (throw)
 import Control.Monad.IO.Class (MonadIO (..))
 import Data.Data
-import Data.Typeable
+import Data.Typeable (Typeable)
 import Data.IORef
 import qualified Data.Map as Map
 import Data.Maybe
@@ -61,6 +62,7 @@
 import Data.ByteString (ByteString)
 import qualified Data.ByteString.Char8 as B8
 import qualified Data.Text as T
+import Data.Text.Read (rational)
 import qualified Data.Text.Encoding as T
 import qualified Data.Text.IO as T
 import qualified Blaze.ByteString.Builder.Char8 as BBB
@@ -77,6 +79,7 @@
 import Data.Monoid ((<>))
 import Data.Pool (Pool)
 import Data.Time (utc, localTimeToUTC)
+import Control.Exception (Exception, throwIO)
 
 -- | A @libpq@ connection string.  A simple example of connection
 -- string would be @\"host=localhost port=5432 user=test
@@ -86,7 +89,15 @@
 -- for more details on how to create such strings.
 type ConnectionString = ByteString
 
+-- | PostgresServerVersionError exception. This is thrown when persistent
+-- is unable to find the version of the postgreSQL server.
+data PostgresServerVersionError = PostgresServerVersionError String deriving Typeable
 
+instance Show PostgresServerVersionError where
+    show (PostgresServerVersionError uniqueMsg) =
+      "Unexpected PostgreSQL server version, got " <> uniqueMsg
+instance Exception PostgresServerVersionError
+
 -- | Create a PostgreSQL connection pool and run the given
 -- action.  The pool is properly released after the action
 -- finishes using it.  Note that you should not use the given
@@ -148,16 +159,38 @@
     modConn conn
     openSimpleConn logFunc conn
 
+-- | Gets the PostgreSQL server version
+getServerVersion :: PG.Connection -> IO (Maybe Double)
+getServerVersion conn = do
+  [PG.Only version] <- PG.query_ conn "show server_version";
+  let version' = rational version
+  --- λ> rational "9.8.3"
+  --- Right (9.8,".3")
+  --- λ> rational "9.8.3.5"
+  --- Right (9.8,".3.5")
+  case version' of
+    Right (a,_) -> return $ Just a
+    Left err -> throwIO $ PostgresServerVersionError err
 
+-- | Choose upsert sql generation function based on postgresql version.
+-- PostgreSQL version >= 9.5 supports native upsert feature,
+-- so depending upon that we have to choose how the sql query is generated.
+upsertFunction :: Double -> Maybe (EntityDef -> Text -> Text)
+upsertFunction version = if (version >= 9.5)
+                         then Just upsertSql'
+                         else Nothing
+
 -- | Generate a 'Connection' from a 'PG.Connection'
 openSimpleConn :: (IsSqlBackend backend) => LogFunc -> PG.Connection -> IO backend
 openSimpleConn logFunc conn = do
     smap <- newIORef $ Map.empty
+    serverVersion <- getServerVersion conn
     return . mkPersistBackend $ SqlBackend
         { connPrepare    = prepare' conn
         , connStmtMap    = smap
         , connInsertSql  = insertSql'
         , connInsertManySql = Just insertManySql'
+        , connUpsertSql = maybe Nothing upsertFunction serverVersion
         , connClose      = PG.close conn
         , connMigrateSql = migrate'
         , connBegin      = const $ PG.begin    conn
@@ -199,6 +232,32 @@
        Just _pdef -> ISRManyKeys sql vals
        Nothing -> ISRSingle (sql <> " RETURNING " <> escape (fieldDB (entityId ent)))
 
+
+upsertSql' :: EntityDef -> Text -> Text
+upsertSql' ent updateVal = T.concat
+                           [ "INSERT INTO "
+                           , escape (entityDB ent)
+                           , "("
+                           , T.intercalate "," $ map (escape . fieldDB) $ entityFields ent
+                           , ") VALUES ("
+                           , T.intercalate "," $ map (const "?") (entityFields ent)
+                           , ") ON CONFLICT ("
+                           , T.intercalate "," $ concat $ map (\x -> map escape (map snd $ uniqueFields x)) (entityUniques ent)
+                           , ") DO UPDATE SET "
+                           , updateVal
+                           , " WHERE "
+                           , wher
+                           , " RETURNING ??"
+                           ]
+    where
+      wher = T.intercalate " AND " $ map singleCondition $ entityUniques ent
+
+      singleCondition :: UniqueDef -> Text
+      singleCondition udef = T.intercalate " AND " (map singleClause $ map snd (uniqueFields udef))
+
+      singleClause :: DBName -> Text
+      singleClause field = escape (entityDB ent) <> "." <> (escape field) <> " =?"
+
 -- | SQL for inserting multiple rows at once and returning their primary keys.
 insertManySql' :: EntityDef -> [[PersistValue]] -> InsertSqlResult
 insertManySql' ent valss =
@@ -1041,6 +1100,7 @@
                                                         },
                              connInsertManySql = Nothing,
                              connInsertSql = undefined,
+                             connUpsertSql = Nothing,
                              connStmtMap = smap,
                              connClose = undefined,
                              connMigrateSql = mockMigrate,
diff --git a/persistent-postgresql.cabal b/persistent-postgresql.cabal
--- a/persistent-postgresql.cabal
+++ b/persistent-postgresql.cabal
@@ -1,5 +1,5 @@
 name:            persistent-postgresql
-version:         2.5
+version:         2.6
 license:         MIT
 license-file:    LICENSE
 author:          Felipe Lessa, Michael Snoyman <michael@snoyman.com>
@@ -19,7 +19,7 @@
                    , transformers          >= 0.2.1
                    , postgresql-simple     >= 0.4.0    && < 0.6
                    , postgresql-libpq      >= 0.6.1    && < 0.10
-                   , persistent            >= 2.5      && < 3
+                   , persistent            >= 2.6      && < 3
                    , containers            >= 0.2
                    , bytestring            >= 0.9
                    , text                  >= 0.7