diff --git a/CHANGELOG.md b/CHANGELOG.md
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--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,5 @@
+# Revision history for ghc-experimental
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright (c) 2023, ghc-devs@haskell.org
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of ghc-devs@haskell.org nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/ghc-experimental.cabal b/ghc-experimental.cabal
new file mode 100644
--- /dev/null
+++ b/ghc-experimental.cabal
@@ -0,0 +1,38 @@
+cabal-version:      3.0
+name:               ghc-experimental
+version:            0.1.0.0
+synopsis:           Experimental features of GHC's standard library
+description:
+    This package is where experimental GHC standard library interfaces start
+    life and mature. Eventually, stabilized interfaces will be
+    migrated into the @base@ library.
+
+homepage:           https://www.haskell.org/ghc/
+license:            BSD-3-Clause
+license-file:       LICENSE
+author:             The GHC Team
+maintainer:         ghc-devs@haskell.org
+copyright:          (c) 2023 The GHC Team
+category:           Development
+build-type:         Simple
+extra-doc-files:    CHANGELOG.md
+
+common warnings
+    ghc-options: -Wall
+
+library
+    import:           warnings
+    exposed-modules:
+      GHC.Profiling.Eras
+      Data.Tuple.Experimental
+      Data.Sum.Experimental
+      Prelude.Experimental
+    if arch(wasm32)
+        exposed-modules:  GHC.Wasm.Prim
+    other-extensions:
+    build-depends:    base ^>=4.20,
+                      ghc-internal >= 9.1001 && < 9.1002,
+                      ghc-prim >= 0.11 && < 0.12
+    hs-source-dirs:   src
+    default-language: Haskell2010
+    ghc-options: -this-unit-id ghc-experimental
diff --git a/src/Data/Sum/Experimental.hs b/src/Data/Sum/Experimental.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Sum/Experimental.hs
@@ -0,0 +1,84 @@
+{-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE NoImplicitPrelude, MagicHash, UnboxedSums, NoListTuplePuns #-}
+
+{-
+Module      :  Data.Sum.Experimental
+Copyright   :  (c) The GHC Team
+License     :  see libraries/ghc-experimental/LICENSE
+
+Maintainer  :  ghc-devs@haskell.org
+Stability   :  experimental
+Portability :  non-portable (GHC extensions)
+
+This module exports the new user-syntax types for unboxed sums, which avoid the
+ambiguity of the old punned names.
+See the proposal for motivation and explanations:
+https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0475-tuple-syntax.rst
+-}
+module Data.Sum.Experimental (
+  Sum2#,
+  Sum3#,
+  Sum4#,
+  Sum5#,
+  Sum6#,
+  Sum7#,
+  Sum8#,
+  Sum9#,
+  Sum10#,
+  Sum11#,
+  Sum12#,
+  Sum13#,
+  Sum14#,
+  Sum15#,
+  Sum16#,
+  Sum17#,
+  Sum18#,
+  Sum19#,
+  Sum20#,
+  Sum21#,
+  Sum22#,
+  Sum23#,
+  Sum24#,
+  Sum25#,
+  Sum26#,
+  Sum27#,
+  Sum28#,
+  Sum29#,
+  Sum30#,
+  Sum31#,
+  Sum32#,
+  Sum33#,
+  Sum34#,
+  Sum35#,
+  Sum36#,
+  Sum37#,
+  Sum38#,
+  Sum39#,
+  Sum40#,
+  Sum41#,
+  Sum42#,
+  Sum43#,
+  Sum44#,
+  Sum45#,
+  Sum46#,
+  Sum47#,
+  Sum48#,
+  Sum49#,
+  Sum50#,
+  Sum51#,
+  Sum52#,
+  Sum53#,
+  Sum54#,
+  Sum55#,
+  Sum56#,
+  Sum57#,
+  Sum58#,
+  Sum59#,
+  Sum60#,
+  Sum61#,
+  Sum62#,
+  Sum63#,
+) where
+
+import GHC.Num.BigNat () -- for build ordering
+import GHC.Types
diff --git a/src/Data/Tuple/Experimental.hs b/src/Data/Tuple/Experimental.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Tuple/Experimental.hs
@@ -0,0 +1,164 @@
+{-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE NoImplicitPrelude, MagicHash, UnboxedTuples, NoListTuplePuns #-}
+
+{-
+Module      :  Data.Tuple.Experimental
+Copyright   :  (c) The GHC Team
+License     :  see libraries/ghc-experimental/LICENSE
+
+Maintainer  :  ghc-devs@haskell.org
+Stability   :  experimental
+Portability :  non-portable (GHC extensions)
+
+This module exports the new user-syntax types for (boxed, unboxed, constraint)
+tuples, which avoid the ambiguity of the old punned names.
+See the proposal for motivation and explanations:
+https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0475-tuple-syntax.rst
+-}
+module Data.Tuple.Experimental (
+  module GHC.Tuple,
+  Solo (Solo, MkSolo),
+
+  -- * Unboxed tuples
+  Unit#,
+  Solo#,
+  Tuple0#,
+  Tuple1#,
+  Tuple2#,
+  Tuple3#,
+  Tuple4#,
+  Tuple5#,
+  Tuple6#,
+  Tuple7#,
+  Tuple8#,
+  Tuple9#,
+  Tuple10#,
+  Tuple11#,
+  Tuple12#,
+  Tuple13#,
+  Tuple14#,
+  Tuple15#,
+  Tuple16#,
+  Tuple17#,
+  Tuple18#,
+  Tuple19#,
+  Tuple20#,
+  Tuple21#,
+  Tuple22#,
+  Tuple23#,
+  Tuple24#,
+  Tuple25#,
+  Tuple26#,
+  Tuple27#,
+  Tuple28#,
+  Tuple29#,
+  Tuple30#,
+  Tuple31#,
+  Tuple32#,
+  Tuple33#,
+  Tuple34#,
+  Tuple35#,
+  Tuple36#,
+  Tuple37#,
+  Tuple38#,
+  Tuple39#,
+  Tuple40#,
+  Tuple41#,
+  Tuple42#,
+  Tuple43#,
+  Tuple44#,
+  Tuple45#,
+  Tuple46#,
+  Tuple47#,
+  Tuple48#,
+  Tuple49#,
+  Tuple50#,
+  Tuple51#,
+  Tuple52#,
+  Tuple53#,
+  Tuple54#,
+  Tuple55#,
+  Tuple56#,
+  Tuple57#,
+  Tuple58#,
+  Tuple59#,
+  Tuple60#,
+  Tuple61#,
+  Tuple62#,
+  Tuple63#,
+  Tuple64#,
+
+  -- * Constraint tuples
+  CUnit,
+  CSolo,
+  CTuple0,
+  CTuple1,
+  CTuple2,
+  CTuple3,
+  CTuple4,
+  CTuple5,
+  CTuple6,
+  CTuple7,
+  CTuple8,
+  CTuple9,
+  CTuple10,
+  CTuple11,
+  CTuple12,
+  CTuple13,
+  CTuple14,
+  CTuple15,
+  CTuple16,
+  CTuple17,
+  CTuple18,
+  CTuple19,
+  CTuple20,
+  CTuple21,
+  CTuple22,
+  CTuple23,
+  CTuple24,
+  CTuple25,
+  CTuple26,
+  CTuple27,
+  CTuple28,
+  CTuple29,
+  CTuple30,
+  CTuple31,
+  CTuple32,
+  CTuple33,
+  CTuple34,
+  CTuple35,
+  CTuple36,
+  CTuple37,
+  CTuple38,
+  CTuple39,
+  CTuple40,
+  CTuple41,
+  CTuple42,
+  CTuple43,
+  CTuple44,
+  CTuple45,
+  CTuple46,
+  CTuple47,
+  CTuple48,
+  CTuple49,
+  CTuple50,
+  CTuple51,
+  CTuple52,
+  CTuple53,
+  CTuple54,
+  CTuple55,
+  CTuple56,
+  CTuple57,
+  CTuple58,
+  CTuple59,
+  CTuple60,
+  CTuple61,
+  CTuple62,
+  CTuple63,
+  CTuple64,
+) where
+
+import GHC.Tuple
+import GHC.Types
+import GHC.Classes
+import GHC.Num.BigNat () -- for build ordering
diff --git a/src/GHC/Profiling/Eras.hs b/src/GHC/Profiling/Eras.hs
new file mode 100644
--- /dev/null
+++ b/src/GHC/Profiling/Eras.hs
@@ -0,0 +1,19 @@
+{-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+
+module GHC.Profiling.Eras ( setUserEra
+                     , getUserEra
+                     , incrementUserEra
+                     ) where
+
+import GHC.Internal.Base
+
+-- | Set the heap profiling era, setting the era to 0 will stop closures being
+-- counted.
+foreign import ccall setUserEra :: Word -> IO ()
+
+-- | Query the profiling era
+foreign import ccall getUserEra :: IO Word
+
+-- | Increment the era by a given amount, and return the new era.
+foreign import ccall incrementUserEra :: Word -> IO Word
diff --git a/src/GHC/Wasm/Prim.hs b/src/GHC/Wasm/Prim.hs
new file mode 100644
--- /dev/null
+++ b/src/GHC/Wasm/Prim.hs
@@ -0,0 +1,23 @@
+{-# LANGUAGE NoImplicitPrelude #-}
+
+module GHC.Wasm.Prim (
+  -- User-facing JSVal type and freeJSVal
+  JSVal (..),
+  freeJSVal,
+
+  -- The JSString type and conversion from/to Haskell String
+  JSString (..),
+  fromJSString,
+  toJSString,
+
+  -- Exception types related to JSFFI
+  JSException (..),
+  WouldBlockException (..),
+  PromisePendingException (..),
+
+  -- Is JSFFI used in the current wasm module?
+  isJSFFIUsed
+) where
+
+import GHC.Internal.Wasm.Prim
+
diff --git a/src/Prelude/Experimental.hs b/src/Prelude/Experimental.hs
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--- /dev/null
+++ b/src/Prelude/Experimental.hs
@@ -0,0 +1,30 @@
+{-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# OPTIONS_HADDOCK not-home #-}
+
+{-
+Module      :  Prelude.Experimental
+Copyright   :  (c) The GHC Team
+License     :  see libraries/ghc-experimental/LICENSE
+
+Maintainer  :  libraries@haskell.org
+Stability   :  experimental
+Portability :  non-portable (GHC extensions)
+
+The Prelude for ghc-experimental, re-exporting definitions peculiar to GHC that
+are safe to use in ordinary code, but whose API may evolve rapidly over
+subsequent releases.
+-}
+module Prelude.Experimental (
+  List,
+
+  -- * Tuple/sum syntax families and tycons
+  module Data.Tuple.Experimental,
+  module Data.Sum.Experimental,
+) where
+
+import GHC.Types (List)
+import GHC.Classes
+
+import Data.Tuple.Experimental
+import Data.Sum.Experimental