diff --git a/build_sysroot/alloc_system/lib.rs b/build_sysroot/alloc_system/lib.rs
index 74b52a6497e..a942fa8d95e 100644
--- a/build_sysroot/alloc_system/lib.rs
+++ b/build_sysroot/alloc_system/lib.rs
@@ -23,7 +23,6 @@
     feature(integer_atomics, stdsimd)
 )]
 #![cfg_attr(any(unix, target_os = "cloudabi", target_os = "redox"), feature(libc))]
-#![rustc_alloc_kind = "lib"]
 // The minimum alignment guaranteed by the architecture. This value is used to
 // add fast paths for low alignment values.
 #[cfg(all(any(target_arch = "x86",
diff --git a/example/example.rs b/example/example.rs
index d7fbb932240..e8ddc4aaea1 100644
--- a/example/example.rs
+++ b/example/example.rs
@@ -137,10 +137,6 @@ unsafe fn transmute(c: char) -> u32 {
     intrinsics::transmute(c)
 }
 
-unsafe fn call_uninit() -> u8 {
-    intrinsics::uninit()
-}
-
 unsafe fn deref_str_ptr(s: *const str) -> &'static str {
     &*s
 }
diff --git a/example/mini_core.rs b/example/mini_core.rs
index 56ab9578e78..d900776c55c 100644
--- a/example/mini_core.rs
+++ b/example/mini_core.rs
@@ -1,4 +1,4 @@
-#![feature(no_core, lang_items, intrinsics, unboxed_closures, type_ascription, extern_types)]
+#![feature(no_core, lang_items, intrinsics, unboxed_closures, type_ascription, extern_types, untagged_unions)]
 #![no_core]
 #![allow(dead_code)]
 
@@ -371,6 +371,11 @@ pub trait Drop {
     fn drop(&mut self);
 }
 
+pub union MaybeUninit<T> {
+    pub uninit: (),
+    pub value: T,
+}
+
 pub mod intrinsics {
     extern "rust-intrinsic" {
         pub fn abort() -> !;
@@ -380,7 +385,6 @@ pub mod intrinsics {
         pub fn min_align_of_val<T: ?::Sized>(val: &T) -> usize;
         pub fn copy<T>(src: *const T, dst: *mut T, count: usize);
         pub fn transmute<T, U>(e: T) -> U;
-        pub fn uninit<T>() -> T;
         pub fn init<T>() -> T;
         pub fn ctlz_nonzero<T>(x: T) -> T;
         pub fn needs_drop<T>() -> bool;
diff --git a/example/mini_core_hello_world.rs b/example/mini_core_hello_world.rs
index f9e820da76c..e51f257f6b4 100644
--- a/example/mini_core_hello_world.rs
+++ b/example/mini_core_hello_world.rs
@@ -181,15 +181,15 @@ fn main() {
         }
 
         unsafe fn uninitialized<T>() -> T {
-            intrinsics::uninit::<T>()
+            MaybeUninit { uninit: () }.value
         }
 
+        zeroed::<(u8, u8)>();
         #[allow(unreachable_code)]
         {
             if false {
                 zeroed::<!>();
                 zeroed::<Foo>();
-                zeroed::<(u8, u8)>();
                 uninitialized::<Foo>();
             }
         }
diff --git a/src/constant.rs b/src/constant.rs
index c13cc72b88d..94007c83587 100644
--- a/src/constant.rs
+++ b/src/constant.rs
@@ -5,7 +5,7 @@ use rustc::mir::interpret::{
 };
 use rustc::ty::Const;
 use rustc_mir::interpret::{
-    InterpretCx, ImmTy, Machine, Memory, MemoryKind, OpTy, PlaceTy,
+    InterpCx, ImmTy, Machine, Memory, MemoryKind, OpTy, PlaceTy,
     StackPopCleanup,
 };
 
@@ -141,10 +141,11 @@ fn trans_const_place<'a, 'tcx: 'a>(
 ) -> CPlace<'tcx> {
     // Adapted from https://github.com/rust-lang/rust/pull/53671/files#diff-e0b58bb6712edaa8595ad7237542c958L551
     let result = || -> InterpResult<'tcx, &'tcx Allocation> {
-        let mut ecx = InterpretCx::new(
+        let mut ecx = InterpCx::new(
             fx.tcx.at(DUMMY_SP),
             ty::ParamEnv::reveal_all(),
             TransPlaceInterpreter,
+            (),
         );
         ecx.push_stack_frame(
             fx.instance,
@@ -242,7 +243,7 @@ fn define_all_allocs(
     module: &mut Module<impl Backend>,
     cx: &mut ConstantCx,
 ) {
-    let memory = Memory::<TransPlaceInterpreter>::new(tcx.at(DUMMY_SP));
+    let memory = Memory::<TransPlaceInterpreter>::new(tcx.at(DUMMY_SP), ());
 
     while let Some(todo_item) = pop_set(&mut cx.todo) {
         let (data_id, alloc) = match todo_item {
@@ -338,23 +339,25 @@ struct TransPlaceInterpreter;
 
 impl<'mir, 'tcx> Machine<'mir, 'tcx> for TransPlaceInterpreter {
     type MemoryKinds = !;
+    type ExtraFnVal = !;
     type PointerTag = ();
     type AllocExtra = ();
     type MemoryExtra = ();
     type FrameExtra = ();
     type MemoryMap = FxHashMap<AllocId, (MemoryKind<!>, Allocation<()>)>;
+
     const STATIC_KIND: Option<!> = None;
 
-    fn enforce_validity(_: &InterpretCx<'mir, 'tcx, Self>) -> bool {
+    fn enforce_validity(_: &InterpCx<'mir, 'tcx, Self>) -> bool {
         false
     }
 
-    fn before_terminator(_: &mut InterpretCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
+    fn before_terminator(_: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
         panic!();
     }
 
     fn find_fn(
-        _: &mut InterpretCx<'mir, 'tcx, Self>,
+        _: &mut InterpCx<'mir, 'tcx, Self>,
         _: Instance<'tcx>,
         _: &[OpTy<'tcx>],
         _: Option<PlaceTy<'tcx>>,
@@ -364,7 +367,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for TransPlaceInterpreter {
     }
 
     fn call_intrinsic(
-        _: &mut InterpretCx<'mir, 'tcx, Self>,
+        _: &mut InterpCx<'mir, 'tcx, Self>,
         _: Instance<'tcx>,
         _: &[OpTy<'tcx>],
         _: PlaceTy<'tcx>,
@@ -373,14 +376,14 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for TransPlaceInterpreter {
     }
 
     fn find_foreign_static(
+        _: TyCtxt<'tcx>,
         _: DefId,
-        _: ::rustc::ty::query::TyCtxtAt<'tcx>,
     ) -> InterpResult<'tcx, Cow<'tcx, Allocation>> {
         panic!();
     }
 
     fn ptr_op(
-        _: &InterpretCx<'mir, 'tcx, Self>,
+        _: &InterpCx<'mir, 'tcx, Self>,
         _: mir::BinOp,
         _: ImmTy<'tcx>,
         _: ImmTy<'tcx>,
@@ -388,28 +391,38 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for TransPlaceInterpreter {
         panic!();
     }
 
-    fn box_alloc(_: &mut InterpretCx<'mir, 'tcx, Self>, _: PlaceTy<'tcx>) -> InterpResult<'tcx> {
+    fn box_alloc(_: &mut InterpCx<'mir, 'tcx, Self>, _: PlaceTy<'tcx>) -> InterpResult<'tcx> {
         panic!();
     }
 
     fn tag_allocation<'b>(
+        _: &(),
         _: AllocId,
         alloc: Cow<'b, Allocation>,
         _: Option<MemoryKind<!>>,
-        _: &Memory<'mir, 'tcx, Self>,
     ) -> (Cow<'b, Allocation<(), ()>>, ()) {
         (alloc, ())
     }
 
-    fn tag_static_base_pointer(_: AllocId, _: &Memory<'mir, 'tcx, Self>) -> Self::PointerTag {
+    fn tag_static_base_pointer(_: &(), _: AllocId) -> Self::PointerTag {
         ()
     }
 
-    fn stack_push(_: &mut InterpretCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
+    fn call_extra_fn(
+        _: &mut InterpCx<'mir, 'tcx, Self>,
+        _: !,
+        _: &[OpTy<'tcx, ()>],
+        _: Option<PlaceTy<'tcx, ()>>,
+        _: Option<BasicBlock>,
+    ) -> InterpResult<'tcx> {
+        unreachable!();
+    }
+
+    fn stack_push(_: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
         Ok(())
     }
 
-    fn stack_pop(_: &mut InterpretCx<'mir, 'tcx, Self>, _: ()) -> InterpResult<'tcx> {
+    fn stack_pop(_: &mut InterpCx<'mir, 'tcx, Self>, _: ()) -> InterpResult<'tcx> {
         Ok(())
     }
 }
diff --git a/src/intrinsics.rs b/src/intrinsics.rs
index f8d5c0c0da4..fbdbf927e2d 100644
--- a/src/intrinsics.rs
+++ b/src/intrinsics.rs
@@ -389,16 +389,6 @@ pub fn codegen_intrinsic_call<'a, 'tcx: 'a>(
             let dst_ptr = dst.load_scalar(fx);
             fx.bcx.call_memset(fx.module.target_config(), dst_ptr, val, count);
         };
-        uninit, <T> () {
-            if ret.layout().abi == Abi::Uninhabited {
-                crate::trap::trap_panic(fx, "[panic] Called intrinsic::uninit for uninhabited type.");
-                return;
-            }
-
-            let uninit_place = CPlace::new_stack_slot(fx, T);
-            let uninit_val = uninit_place.to_cvalue(fx);
-            ret.write_cvalue(fx, uninit_val);
-        };
         ctlz | ctlz_nonzero, <T> (v arg) {
             let res = CValue::by_val(fx.bcx.ins().clz(arg), fx.layout_of(T));
             ret.write_cvalue(fx, res);