diff --git a/cardano-api/src/Cardano/Api.hs b/cardano-api/src/Cardano/Api.hs
index 6fd31a8c689..b4ae9656601 100644
--- a/cardano-api/src/Cardano/Api.hs
+++ b/cardano-api/src/Cardano/Api.hs
@@ -695,6 +695,7 @@ module Cardano.Api (
 
     EraHistory(..),
     getProgress,
+    getSlotForRelativeTime,
 
     -- *** Common queries
     determineEra,
diff --git a/cardano-api/src/Cardano/Api/Query.hs b/cardano-api/src/Cardano/Api/Query.hs
index f655f620791..78ca50186c8 100644
--- a/cardano-api/src/Cardano/Api/Query.hs
+++ b/cardano-api/src/Cardano/Api/Query.hs
@@ -71,6 +71,7 @@ module Cardano.Api.Query (
     LedgerState(..),
 
     getProgress,
+    getSlotForRelativeTime,
 
     -- * Internal conversion functions
     toLedgerUTxO,
@@ -95,6 +96,8 @@ import           Data.SOP.Strict (SListI)
 import           Data.Text (Text)
 import qualified Data.Text as Text
 import           Data.Typeable
+import           Data.Word (Word64)
+import qualified Data.Aeson.KeyMap as KeyMap
 
 import           Ouroboros.Network.Protocol.LocalStateQuery.Client (Some (..))
 
@@ -142,9 +145,7 @@ import           Cardano.Api.NetworkId
 import           Cardano.Api.ProtocolParameters
 import           Cardano.Api.TxBody
 import           Cardano.Api.Value
-import           Data.Word (Word64)
 
-import qualified Data.Aeson.KeyMap as KeyMap
 
 -- ----------------------------------------------------------------------------
 -- Queries
@@ -192,6 +193,11 @@ data EraHistory mode where
 getProgress :: SlotNo -> EraHistory mode -> Either Qry.PastHorizonException (RelativeTime, SlotLength)
 getProgress slotNo (EraHistory _ interpreter) = Qry.interpretQuery interpreter (Qry.slotToWallclock slotNo)
 
+-- | Returns the slot number for provided relative time from 'SystemStart'
+getSlotForRelativeTime :: RelativeTime -> EraHistory mode -> Either Qry.PastHorizonException SlotNo
+getSlotForRelativeTime relTime (EraHistory _ interpreter) = do
+  (slotNo, _, _) <- Qry.interpretQuery interpreter $ Qry.wallclockToSlot relTime
+  pure slotNo
 
 newtype LedgerEpochInfo = LedgerEpochInfo { unLedgerEpochInfo :: Consensus.EpochInfo (Either Text) }
 
diff --git a/cardano-cli/src/Cardano/CLI/Shelley/Run/Query.hs b/cardano-cli/src/Cardano/CLI/Shelley/Run/Query.hs
index a3ddc639adf..5611a38143b 100644
--- a/cardano-cli/src/Cardano/CLI/Shelley/Run/Query.hs
+++ b/cardano-cli/src/Cardano/CLI/Shelley/Run/Query.hs
@@ -20,6 +20,7 @@ module Cardano.CLI.Shelley.Run.Query
   , renderLocalStateQueryError
   , runQueryCmd
   , toEpochInfo
+  , utcTimeToSlotNo
   , determineEra
   , mergeDelegsAndRewards
   , percentage
@@ -32,7 +33,8 @@ import           Cardano.Api.Byron
 import           Cardano.Api.Orphans ()
 import           Cardano.Api.Shelley
 
-import           Control.Monad.Trans.Except (ExceptT (..), except, runExcept, runExceptT)
+import           Control.Monad.Trans.Except (ExceptT (..), except, runExcept, runExceptT,
+                   withExceptT)
 import           Control.Monad.Trans.Except.Extra (firstExceptT, handleIOExceptT, hoistEither,
                    hoistMaybe, left, onLeft, onNothing)
 import           Data.Aeson as Aeson
@@ -90,7 +92,7 @@ import qualified Ouroboros.Consensus.HardFork.History.Qry as Qry
 import qualified Ouroboros.Consensus.Protocol.Abstract as Consensus
 import qualified Ouroboros.Consensus.Protocol.Praos.Common as Consensus
 
-import           Control.Monad (forM, forM_, join, foldM)
+import           Control.Monad (forM, forM_, join)
 import           Control.Monad.IO.Class (MonadIO)
 import           Control.Monad.IO.Unlift (MonadIO (..))
 import           Control.Monad.Trans.Class
@@ -1422,43 +1424,25 @@ toTentativeEpochInfo (EraHistory _ interpreter) =
     $ hoistEpochInfo (first (Text.pack . show) . runExcept)
     $ Consensus.interpreterToEpochInfo (Consensus.unsafeExtendSafeZone interpreter)
 
+
+-- | Get slot number for timestamp, or an error if the UTC timestamp is before 'SystemStart'
 utcTimeToSlotNo
-  :: Maybe SocketPath -> AnyConsensusModeParams -> NetworkId -> UTCTime -> ExceptT ShelleyQueryCmdError IO SlotNo
-utcTimeToSlotNo mNodeSocketPath (AnyConsensusModeParams cModeParams) network utcTime = do
-  SocketPath sockPath <- maybe (lift readEnvSocketPath) (pure . Right) mNodeSocketPath
-    & onLeft (left . ShelleyQueryCmdEnvVarSocketErr)
-  let cMode = consensusModeOnly cModeParams
-      allEras = [minBound .. maxBound] :: [AnyCardanoEra]
-      localNodeConnInfo = LocalNodeConnectInfo cModeParams network sockPath
-  epochInfos <- case cMode of
+  :: SocketPath
+  -> AnyConsensusModeParams
+  -> NetworkId
+  -> UTCTime
+  -> ExceptT ShelleyQueryCmdError IO SlotNo
+utcTimeToSlotNo (SocketPath sockPath) (AnyConsensusModeParams cModeParams) network utcTime = do
+  let localNodeConnInfo = LocalNodeConnectInfo cModeParams network sockPath
+  case consensusModeOnly cModeParams of
     CardanoMode -> do
-      forM allEras $ \anyE@(AnyCardanoEra era) -> do
-        sbe <- getSbe (cardanoEraStyle era)
-        eInMode <- toEraInMode era cMode
-            & hoistMaybe (ShelleyQueryCmdEraConsensusModeMismatch (AnyConsensusMode cMode) anyE)
-        let pparamsQuery = QueryInEra eInMode $ QueryInShelleyBasedEra sbe QueryProtocolParameters
-            ptclStateQuery = QueryInEra eInMode . QueryInShelleyBasedEra sbe $ QueryProtocolState
-            eraHistoryQuery = QueryEraHistory CardanoModeIsMultiEra
-
-        pparams <- executeQuery era cModeParams localNodeConnInfo pparamsQuery
-        ptclState <- executeQuery era cModeParams localNodeConnInfo ptclStateQuery
-        eraHistory <- lift (queryNodeLocalState localNodeConnInfo Nothing eraHistoryQuery)
-          & onLeft (left . ShelleyQueryCmdAcquireFailure)
-
-        pure $ toEpochInfo eraHistory
-
+      (systemStart, eraHistory) <- withExceptT ShelleyQueryCmdAcquireFailure $
+        (,) <$> (ExceptT $ queryNodeLocalState localNodeConnInfo Nothing QuerySystemStart)
+            <*> (ExceptT $ queryNodeLocalState localNodeConnInfo Nothing (QueryEraHistory CardanoModeIsMultiEra))
+      let relTime = toRelativeTime systemStart utcTime
+      hoistEither $ Api.getSlotForRelativeTime relTime eraHistory & first ShelleyQueryCmdPastHorizon
     mode -> left . ShelleyQueryCmdUnsupportedMode $ AnyConsensusMode mode
 
-  let systemStart = undefined :: UTCTime -- FIXME: byron genesis block time
-
-  foldl' findSlot (0, SystemStart systemStart)
-    where
-      findSlot (slotNo, lastSlotTime) epochInfo
-        | lastSlotTime > utcTime = slotNo
-        | otherwise = do
-          let (firstSlot, lastSlot) = epochInfoRange epochInfo
-
-
 
 obtainLedgerEraClassConstraints
   :: ShelleyLedgerEra era ~ ledgerera