diff --git a/cli/src/repl/eval.rs b/cli/src/repl/eval.rs
index 94f51ec6cf..21304feab9 100644
--- a/cli/src/repl/eval.rs
+++ b/cli/src/repl/eval.rs
@@ -116,7 +116,7 @@ fn jit_to_ast_help<'a>(
                 }
             }))
         }
-        Layout::Builtin(Builtin::List(_, elem_layout)) => Ok(run_jit_function!(
+        Layout::Builtin(Builtin::List(elem_layout)) => Ok(run_jit_function!(
             lib,
             main_fn_name,
             (*const u8, usize),
@@ -125,12 +125,6 @@ fn jit_to_ast_help<'a>(
         Layout::Builtin(other) => {
             todo!("add support for rendering builtin {:?} to the REPL", other)
         }
-        Layout::PhantomEmptyStruct => Ok(run_jit_function!(lib, main_fn_name, &u8, |_| {
-            Expr::Record {
-                fields: &[],
-                final_comments: env.arena.alloc([]),
-            }
-        })),
         Layout::Struct(field_layouts) => {
             let ptr_to_ast = |ptr: *const u8| match content {
                 Content::Structure(FlatType::Record(fields, _)) => {
@@ -247,7 +241,6 @@ fn jit_to_ast_help<'a>(
 
         Layout::Closure(_, _, _) => Err(ToAstProblem::FunctionLayout),
         Layout::FunctionPointer(_, _) => Err(ToAstProblem::FunctionLayout),
-        Layout::Pointer(_) => todo!("add support for rendering pointers in the REPL"),
     }
 }
 
@@ -298,7 +291,7 @@ fn ptr_to_ast<'a>(
             items: &[],
             final_comments: &[],
         },
-        Layout::Builtin(Builtin::List(_, elem_layout)) => {
+        Layout::Builtin(Builtin::List(elem_layout)) => {
             // Turn the (ptr, len) wrapper struct into actual ptr and len values.
             let len = unsafe { *(ptr.offset(env.ptr_bytes as isize) as *const usize) };
             let ptr = unsafe { *(ptr as *const *const u8) };
diff --git a/compiler/gen/src/llvm/build.rs b/compiler/gen/src/llvm/build.rs
index c1a0006844..c5e9cdd7c8 100644
--- a/compiler/gen/src/llvm/build.rs
+++ b/compiler/gen/src/llvm/build.rs
@@ -906,9 +906,7 @@ pub fn build_exp_expr<'a, 'ctx, 'env>(
             arguments,
             tag_layout,
             ..
-        } if *union_size == 1
-            && matches!(tag_layout, Layout::Union(UnionLayout::NonRecursive(_))) =>
-        {
+        } if *union_size == 1 && matches!(tag_layout, UnionLayout::NonRecursive(_)) => {
             let it = arguments.iter();
 
             let ctx = env.context;
@@ -956,7 +954,7 @@ pub fn build_exp_expr<'a, 'ctx, 'env>(
 
         Tag {
             arguments,
-            tag_layout: Layout::Union(UnionLayout::NonRecursive(fields)),
+            tag_layout: UnionLayout::NonRecursive(fields),
             union_size,
             tag_id,
             ..
@@ -1044,7 +1042,7 @@ pub fn build_exp_expr<'a, 'ctx, 'env>(
         }
         Tag {
             arguments,
-            tag_layout: Layout::Union(UnionLayout::Recursive(fields)),
+            tag_layout: UnionLayout::Recursive(fields),
             union_size,
             tag_id,
             ..
@@ -1119,7 +1117,7 @@ pub fn build_exp_expr<'a, 'ctx, 'env>(
 
         Tag {
             arguments,
-            tag_layout: Layout::Union(UnionLayout::NonNullableUnwrapped(fields)),
+            tag_layout: UnionLayout::NonNullableUnwrapped(fields),
             union_size,
             tag_id,
             ..
@@ -1195,10 +1193,10 @@ pub fn build_exp_expr<'a, 'ctx, 'env>(
         Tag {
             arguments,
             tag_layout:
-                Layout::Union(UnionLayout::NullableWrapped {
+                UnionLayout::NullableWrapped {
                     nullable_id,
                     other_tags: fields,
-                }),
+                },
             union_size,
             tag_id,
             ..
@@ -1287,11 +1285,11 @@ pub fn build_exp_expr<'a, 'ctx, 'env>(
         Tag {
             arguments,
             tag_layout:
-                Layout::Union(UnionLayout::NullableUnwrapped {
+                UnionLayout::NullableUnwrapped {
                     nullable_id,
                     other_fields,
                     ..
-                }),
+                },
             union_size,
             tag_id,
             tag_name,
@@ -1387,8 +1385,6 @@ pub fn build_exp_expr<'a, 'ctx, 'env>(
             data_ptr.into()
         }
 
-        Tag { .. } => unreachable!("tags should have a Union or RecursiveUnion layout"),
-
         Reset(_) => todo!(),
         Reuse { .. } => todo!(),
 
@@ -2180,7 +2176,7 @@ pub fn build_exp_stmt<'a, 'ctx, 'env>(
                     let (value, layout) = load_symbol_and_layout(scope, symbol);
 
                     match layout {
-                        Layout::Builtin(Builtin::List(_, _)) => {
+                        Layout::Builtin(Builtin::List(_)) => {
                             debug_assert!(value.is_struct_value());
 
                             // because of how we insert DECREF for lists, we can't guarantee that
@@ -3360,11 +3356,9 @@ pub fn build_proc<'a, 'ctx, 'env>(
                     }
 
                     Layout::Builtin(_) => {}
-                    Layout::PhantomEmptyStruct => {}
                     Layout::Struct(_) => {}
                     Layout::Union(_) => {}
                     Layout::RecursivePointer => {}
-                    Layout::Pointer(_) => {}
                 }
             }
         }
@@ -3587,7 +3581,7 @@ fn run_higher_order_low_level<'a, 'ctx, 'env>(
 
             match list_layout {
                 Layout::Builtin(Builtin::EmptyList) => default,
-                Layout::Builtin(Builtin::List(_, element_layout)) => {
+                Layout::Builtin(Builtin::List(element_layout)) => {
                     let argument_layouts = &[**element_layout, *default_layout];
 
                     let roc_function_call = roc_function_call(
@@ -3629,8 +3623,8 @@ fn run_higher_order_low_level<'a, 'ctx, 'env>(
             match (list_layout, return_layout) {
                 (Layout::Builtin(Builtin::EmptyList), _) => empty_list(env),
                 (
-                    Layout::Builtin(Builtin::List(_, element_layout)),
-                    Layout::Builtin(Builtin::List(_, result_layout)),
+                    Layout::Builtin(Builtin::List(element_layout)),
+                    Layout::Builtin(Builtin::List(result_layout)),
                 ) => {
                     let argument_layouts = &[**element_layout];
 
@@ -3660,9 +3654,9 @@ fn run_higher_order_low_level<'a, 'ctx, 'env>(
 
             match (list1_layout, list2_layout, return_layout) {
                 (
-                    Layout::Builtin(Builtin::List(_, element1_layout)),
-                    Layout::Builtin(Builtin::List(_, element2_layout)),
-                    Layout::Builtin(Builtin::List(_, result_layout)),
+                    Layout::Builtin(Builtin::List(element1_layout)),
+                    Layout::Builtin(Builtin::List(element2_layout)),
+                    Layout::Builtin(Builtin::List(result_layout)),
                 ) => {
                     let argument_layouts = &[**element1_layout, **element2_layout];
 
@@ -3704,10 +3698,10 @@ fn run_higher_order_low_level<'a, 'ctx, 'env>(
 
             match (list1_layout, list2_layout, list3_layout, return_layout) {
                 (
-                    Layout::Builtin(Builtin::List(_, element1_layout)),
-                    Layout::Builtin(Builtin::List(_, element2_layout)),
-                    Layout::Builtin(Builtin::List(_, element3_layout)),
-                    Layout::Builtin(Builtin::List(_, result_layout)),
+                    Layout::Builtin(Builtin::List(element1_layout)),
+                    Layout::Builtin(Builtin::List(element2_layout)),
+                    Layout::Builtin(Builtin::List(element3_layout)),
+                    Layout::Builtin(Builtin::List(result_layout)),
                 ) => {
                     let argument_layouts =
                         &[**element1_layout, **element2_layout, **element3_layout];
@@ -3754,8 +3748,8 @@ fn run_higher_order_low_level<'a, 'ctx, 'env>(
             match (list_layout, return_layout) {
                 (Layout::Builtin(Builtin::EmptyList), _) => empty_list(env),
                 (
-                    Layout::Builtin(Builtin::List(_, element_layout)),
-                    Layout::Builtin(Builtin::List(_, result_layout)),
+                    Layout::Builtin(Builtin::List(element_layout)),
+                    Layout::Builtin(Builtin::List(result_layout)),
                 ) => {
                     let argument_layouts = &[Layout::Builtin(Builtin::Usize), **element_layout];
 
@@ -3786,7 +3780,7 @@ fn run_higher_order_low_level<'a, 'ctx, 'env>(
 
             match list_layout {
                 Layout::Builtin(Builtin::EmptyList) => empty_list(env),
-                Layout::Builtin(Builtin::List(_, element_layout)) => {
+                Layout::Builtin(Builtin::List(element_layout)) => {
                     let argument_layouts = &[**element_layout];
 
                     let roc_function_call = roc_function_call(
@@ -3818,8 +3812,8 @@ fn run_higher_order_low_level<'a, 'ctx, 'env>(
                 (_, Layout::Builtin(Builtin::EmptyList))
                 | (Layout::Builtin(Builtin::EmptyList), _) => empty_list(env),
                 (
-                    Layout::Builtin(Builtin::List(_, before_layout)),
-                    Layout::Builtin(Builtin::List(_, after_layout)),
+                    Layout::Builtin(Builtin::List(before_layout)),
+                    Layout::Builtin(Builtin::List(after_layout)),
                 ) => {
                     let argument_layouts = &[**before_layout];
 
@@ -3862,8 +3856,8 @@ fn run_higher_order_low_level<'a, 'ctx, 'env>(
                 (_, Layout::Builtin(Builtin::EmptyList))
                 | (Layout::Builtin(Builtin::EmptyList), _) => empty_list(env),
                 (
-                    Layout::Builtin(Builtin::List(_, before_layout)),
-                    Layout::Builtin(Builtin::List(_, after_layout)),
+                    Layout::Builtin(Builtin::List(before_layout)),
+                    Layout::Builtin(Builtin::List(after_layout)),
                 ) => {
                     let argument_layouts = &[**before_layout];
 
@@ -3913,7 +3907,7 @@ fn run_higher_order_low_level<'a, 'ctx, 'env>(
 
             match list_layout {
                 Layout::Builtin(Builtin::EmptyList) => empty_list(env),
-                Layout::Builtin(Builtin::List(_, element_layout)) => {
+                Layout::Builtin(Builtin::List(element_layout)) => {
                     use crate::llvm::bitcode::build_compare_wrapper;
 
                     let argument_layouts = &[**element_layout, **element_layout];
@@ -4181,7 +4175,7 @@ fn run_low_level<'a, 'ctx, 'env>(
 
             match list_layout {
                 Layout::Builtin(Builtin::EmptyList) => empty_list(env),
-                Layout::Builtin(Builtin::List(_, element_layout)) => list_drop(
+                Layout::Builtin(Builtin::List(element_layout)) => list_drop(
                     env,
                     layout_ids,
                     original_wrapper,
@@ -4450,7 +4444,7 @@ fn run_low_level<'a, 'ctx, 'env>(
                     // no elements, so nothing to remove
                     empty_list(env)
                 }
-                Layout::Builtin(Builtin::List(_, element_layout)) => list_set(
+                Layout::Builtin(Builtin::List(element_layout)) => list_set(
                     env,
                     layout_ids,
                     list,
@@ -4471,7 +4465,7 @@ fn run_low_level<'a, 'ctx, 'env>(
                     // no elements, so nothing to remove
                     empty_list(env)
                 }
-                Layout::Builtin(Builtin::List(_, element_layout)) => list_set(
+                Layout::Builtin(Builtin::List(element_layout)) => list_set(
                     env,
                     layout_ids,
                     list,
@@ -4648,7 +4642,7 @@ fn run_low_level<'a, 'ctx, 'env>(
 
             match list_layout {
                 Layout::Builtin(Builtin::EmptyList) => dict_empty(env),
-                Layout::Builtin(Builtin::List(_, key_layout)) => {
+                Layout::Builtin(Builtin::List(key_layout)) => {
                     set_from_list(env, layout_ids, list, key_layout)
                 }
                 _ => unreachable!("invalid dict layout"),
diff --git a/compiler/gen/src/llvm/build_hash.rs b/compiler/gen/src/llvm/build_hash.rs
index 95db536a88..195ff1f30e 100644
--- a/compiler/gen/src/llvm/build_hash.rs
+++ b/compiler/gen/src/llvm/build_hash.rs
@@ -56,11 +56,6 @@ fn build_hash_layout<'a, 'ctx, 'env>(
             val.into_struct_value(),
         ),
 
-        Layout::PhantomEmptyStruct => {
-            // just does nothing and returns the seed
-            seed
-        }
-
         Layout::Union(union_layout) => {
             build_hash_tag(env, layout_ids, layout, union_layout, seed, val)
         }
@@ -91,10 +86,6 @@ fn build_hash_layout<'a, 'ctx, 'env>(
             }
         },
 
-        Layout::Pointer(_) => {
-            unreachable!("unused")
-        }
-
         Layout::FunctionPointer(_, _) | Layout::Closure(_, _, _) => {
             unreachable!("the type system will guarantee these are never hashed")
         }
@@ -157,7 +148,7 @@ fn hash_builtin<'a, 'ctx, 'env>(
         Builtin::Set(_) => {
             todo!("Implement Hash for Set")
         }
-        Builtin::List(_, element_layout) => build_hash_list(
+        Builtin::List(element_layout) => build_hash_list(
             env,
             layout_ids,
             layout,
diff --git a/compiler/gen/src/llvm/build_list.rs b/compiler/gen/src/llvm/build_list.rs
index f71e4a507a..5a7fea02c9 100644
--- a/compiler/gen/src/llvm/build_list.rs
+++ b/compiler/gen/src/llvm/build_list.rs
@@ -14,7 +14,7 @@ use inkwell::types::{BasicTypeEnum, PointerType};
 use inkwell::values::{BasicValueEnum, FunctionValue, IntValue, PointerValue, StructValue};
 use inkwell::{AddressSpace, IntPredicate};
 use roc_builtins::bitcode;
-use roc_mono::layout::{Builtin, InPlace, Layout, LayoutIds, MemoryMode};
+use roc_mono::layout::{Builtin, InPlace, Layout, LayoutIds};
 
 fn list_returned_from_zig<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
@@ -196,12 +196,12 @@ pub fn list_join<'a, 'ctx, 'env>(
 ) -> BasicValueEnum<'ctx> {
     match outer_list_layout {
         Layout::Builtin(Builtin::EmptyList)
-        | Layout::Builtin(Builtin::List(_, Layout::Builtin(Builtin::EmptyList))) => {
+        | Layout::Builtin(Builtin::List(Layout::Builtin(Builtin::EmptyList))) => {
             // If the input list is empty, or if it is a list of empty lists
             // then simply return an empty list
             empty_list(env)
         }
-        Layout::Builtin(Builtin::List(_, Layout::Builtin(Builtin::List(_, element_layout)))) => {
+        Layout::Builtin(Builtin::List(Layout::Builtin(Builtin::List(element_layout)))) => {
             call_bitcode_fn_returns_list(
                 env,
                 &[
@@ -231,13 +231,7 @@ pub fn list_reverse<'a, 'ctx, 'env>(
             // this pointer will never actually be dereferenced
             Layout::Builtin(Builtin::Int64),
         ),
-        Layout::Builtin(Builtin::List(memory_mode, elem_layout)) => (
-            match memory_mode {
-                MemoryMode::Unique => InPlace::InPlace,
-                MemoryMode::Refcounted => InPlace::Clone,
-            },
-            *elem_layout,
-        ),
+        Layout::Builtin(Builtin::List(elem_layout)) => (InPlace::Clone, *elem_layout),
 
         _ => unreachable!("Invalid layout {:?} in List.reverse", list_layout),
     };
@@ -264,7 +258,7 @@ pub fn list_get_unsafe<'a, 'ctx, 'env>(
     let builder = env.builder;
 
     match list_layout {
-        Layout::Builtin(Builtin::List(_, elem_layout)) => {
+        Layout::Builtin(Builtin::List(elem_layout)) => {
             let elem_type = basic_type_from_layout(env, elem_layout);
             let ptr_type = get_ptr_type(&elem_type, AddressSpace::Generic);
             // Load the pointer to the array data
@@ -861,7 +855,7 @@ pub fn list_concat<'a, 'ctx, 'env>(
             // then simply return an empty list
             empty_list(env)
         }
-        Layout::Builtin(Builtin::List(_, elem_layout)) => call_bitcode_fn_returns_list(
+        Layout::Builtin(Builtin::List(elem_layout)) => call_bitcode_fn_returns_list(
             env,
             &[
                 pass_list_as_i128(env, first_list),
diff --git a/compiler/gen/src/llvm/compare.rs b/compiler/gen/src/llvm/compare.rs
index 0cf32263d0..7f9cf127dd 100644
--- a/compiler/gen/src/llvm/compare.rs
+++ b/compiler/gen/src/llvm/compare.rs
@@ -99,7 +99,7 @@ fn build_eq_builtin<'a, 'ctx, 'env>(
         Builtin::Float16 => float_cmp(FloatPredicate::OEQ, "eq_f16"),
 
         Builtin::Str => str_equal(env, lhs_val, rhs_val),
-        Builtin::List(_, elem) => build_list_eq(
+        Builtin::List(elem) => build_list_eq(
             env,
             layout_ids,
             &Layout::Builtin(*builtin),
@@ -159,11 +159,6 @@ fn build_eq<'a, 'ctx, 'env>(
             rhs_val,
         ),
 
-        Layout::PhantomEmptyStruct => {
-            // always equal to itself
-            env.context.bool_type().const_int(1, false).into()
-        }
-
         Layout::RecursivePointer => match when_recursive {
             WhenRecursive::Unreachable => {
                 unreachable!("recursion pointers should never be compared directly")
@@ -197,10 +192,6 @@ fn build_eq<'a, 'ctx, 'env>(
             }
         },
 
-        Layout::Pointer(_) => {
-            unreachable!("unused")
-        }
-
         Layout::FunctionPointer(_, _) | Layout::Closure(_, _, _) => {
             unreachable!("the type system will guarantee these are never compared")
         }
@@ -258,7 +249,7 @@ fn build_neq_builtin<'a, 'ctx, 'env>(
 
             result.into()
         }
-        Builtin::List(_, elem) => {
+        Builtin::List(elem) => {
             let is_equal = build_list_eq(
                 env,
                 layout_ids,
@@ -338,19 +329,10 @@ fn build_neq<'a, 'ctx, 'env>(
             result.into()
         }
 
-        Layout::PhantomEmptyStruct => {
-            // always equal to itself
-            env.context.bool_type().const_int(1, false).into()
-        }
-
         Layout::RecursivePointer => {
             unreachable!("recursion pointers should never be compared directly")
         }
 
-        Layout::Pointer(_) => {
-            unreachable!("unused")
-        }
-
         Layout::FunctionPointer(_, _) | Layout::Closure(_, _, _) => {
             unreachable!("the type system will guarantee these are never compared")
         }
diff --git a/compiler/gen/src/llvm/convert.rs b/compiler/gen/src/llvm/convert.rs
index 29e874c992..c88c12c18b 100644
--- a/compiler/gen/src/llvm/convert.rs
+++ b/compiler/gen/src/llvm/convert.rs
@@ -112,10 +112,6 @@ pub fn basic_type_from_layout<'a, 'ctx, 'env>(
             let closure_data_layout = closure_layout.runtime_representation();
             basic_type_from_layout(env, &closure_data_layout)
         }
-        Pointer(layout) => basic_type_from_layout(env, &layout)
-            .ptr_type(AddressSpace::Generic)
-            .into(),
-        PhantomEmptyStruct => env.context.struct_type(&[], false).into(),
         Struct(sorted_fields) => basic_type_from_record(env, sorted_fields),
         Union(variant) => {
             use UnionLayout::*;
@@ -174,7 +170,7 @@ pub fn basic_type_from_builtin<'a, 'ctx, 'env>(
         Float16 => context.f16_type().as_basic_type_enum(),
         Dict(_, _) | EmptyDict => zig_dict_type(env).into(),
         Set(_) | EmptySet => zig_dict_type(env).into(),
-        List(_, _) | EmptyList => zig_list_type(env).into(),
+        List(_) | EmptyList => zig_list_type(env).into(),
         Str | EmptyStr => zig_str_type(env).into(),
     }
 }
diff --git a/compiler/gen/src/llvm/refcounting.rs b/compiler/gen/src/llvm/refcounting.rs
index cf0a254163..71c309f8b4 100644
--- a/compiler/gen/src/llvm/refcounting.rs
+++ b/compiler/gen/src/llvm/refcounting.rs
@@ -15,7 +15,7 @@ use inkwell::values::{BasicValueEnum, FunctionValue, IntValue, PointerValue, Str
 use inkwell::{AddressSpace, IntPredicate};
 use roc_module::symbol::Interns;
 use roc_module::symbol::Symbol;
-use roc_mono::layout::{Builtin, Layout, LayoutIds, MemoryMode, UnionLayout};
+use roc_mono::layout::{Builtin, Layout, LayoutIds, UnionLayout};
 
 pub const REFCOUNT_MAX: usize = 0_usize;
 
@@ -469,21 +469,17 @@ fn modify_refcount_builtin<'a, 'ctx, 'env>(
     use Builtin::*;
 
     match builtin {
-        List(memory_mode, element_layout) => {
-            if let MemoryMode::Refcounted = memory_mode {
-                let function = modify_refcount_list(
-                    env,
-                    layout_ids,
-                    mode,
-                    when_recursive,
-                    layout,
-                    element_layout,
-                );
+        List(element_layout) => {
+            let function = modify_refcount_list(
+                env,
+                layout_ids,
+                mode,
+                when_recursive,
+                layout,
+                element_layout,
+            );
 
-                Some(function)
-            } else {
-                None
-            }
+            Some(function)
         }
         Set(element_layout) => {
             let key_layout = &Layout::Struct(&[]);
@@ -724,8 +720,6 @@ fn modify_refcount_layout_build_function<'a, 'ctx, 'env>(
             Some(function)
         }
 
-        PhantomEmptyStruct => None,
-
         Layout::RecursivePointer => match when_recursive {
             WhenRecursive::Unreachable => {
                 unreachable!("recursion pointers should never be hashed directly")
@@ -746,7 +740,7 @@ fn modify_refcount_layout_build_function<'a, 'ctx, 'env>(
             }
         },
 
-        FunctionPointer(_, _) | Pointer(_) => None,
+        FunctionPointer(_, _) => None,
     }
 }
 
@@ -1689,7 +1683,7 @@ pub fn refcount_offset<'a, 'ctx, 'env>(env: &Env<'a, 'ctx, 'env>, layout: &Layou
     let value_bytes = layout.stack_size(env.ptr_bytes) as u64;
 
     match layout {
-        Layout::Builtin(Builtin::List(_, _)) => env.ptr_bytes as u64,
+        Layout::Builtin(Builtin::List(_)) => env.ptr_bytes as u64,
         Layout::Builtin(Builtin::Str) => env.ptr_bytes as u64,
         Layout::RecursivePointer | Layout::Union(_) => env.ptr_bytes as u64,
         _ => (env.ptr_bytes as u64).max(value_bytes),
diff --git a/compiler/mono/src/alias_analysis.rs b/compiler/mono/src/alias_analysis.rs
index ebca28d1a5..dd3590e57c 100644
--- a/compiler/mono/src/alias_analysis.rs
+++ b/compiler/mono/src/alias_analysis.rs
@@ -377,16 +377,6 @@ fn lowlevel_spec(
 }
 
 fn build_variant_types(
-    builder: &mut FuncDefBuilder,
-    layout: &Layout,
-) -> Option<Result<Vec<TypeId>>> {
-    match layout {
-        Layout::Union(union_layout) => Some(build_variant_types_help(builder, union_layout)),
-        _ => None,
-    }
-}
-
-fn build_variant_types_help(
     builder: &mut FuncDefBuilder,
     union_layout: &UnionLayout,
 ) -> Result<Vec<TypeId>> {
@@ -435,7 +425,7 @@ fn expr_spec(
             arguments,
         } => {
             let value_id = build_tuple_value(builder, env, block, arguments)?;
-            let variant_types = build_variant_types(builder, tag_layout).unwrap()?;
+            let variant_types = build_variant_types(builder, tag_layout)?;
             builder.add_make_union(block, &variant_types, *tag_id as u32, value_id)
         }
         Struct(fields) => build_tuple_value(builder, env, block, fields),
@@ -525,16 +515,14 @@ fn layout_spec(builder: &mut FuncDefBuilder, layout: &Layout) -> Result<TypeId>
 
     match layout {
         Builtin(builtin) => builtin_spec(builder, builtin),
-        PhantomEmptyStruct => todo!(),
         Struct(fields) => build_tuple_type(builder, fields),
         Union(union_layout) => {
-            let variant_types = build_variant_types_help(builder, union_layout)?;
+            let variant_types = build_variant_types(builder, union_layout)?;
             builder.add_union_type(&variant_types)
         }
         RecursivePointer => todo!(),
         FunctionPointer(_, _) => todo!(),
         Closure(_, _, _) => todo!(),
-        Pointer(_) => todo!(),
     }
 }
 
@@ -550,7 +538,7 @@ fn builtin_spec(builder: &mut FuncDefBuilder, builtin: &Builtin) -> Result<TypeI
         Str => todo!(),
         Dict(_, _) => todo!(),
         Set(_) => todo!(),
-        List(_, _) => {
+        List(_) => {
             // TODO should incorporate the element type into the name
             Ok(builder.add_named_type(MOD_LIST, TypeName(b"List")))
         }
diff --git a/compiler/mono/src/ir.rs b/compiler/mono/src/ir.rs
index b7660b4c61..4bedd2dae6 100644
--- a/compiler/mono/src/ir.rs
+++ b/compiler/mono/src/ir.rs
@@ -3,8 +3,8 @@
 use self::InProgressProc::*;
 use crate::exhaustive::{Ctor, Guard, RenderAs, TagId};
 use crate::layout::{
-    Builtin, ClosureRepresentation, LambdaSet, Layout, LayoutCache, LayoutProblem, MemoryMode,
-    UnionLayout, WrappedVariant, TAG_SIZE,
+    Builtin, ClosureRepresentation, LambdaSet, Layout, LayoutCache, LayoutProblem, UnionLayout,
+    WrappedVariant, TAG_SIZE,
 };
 use bumpalo::collections::Vec;
 use bumpalo::Bump;
@@ -1150,7 +1150,7 @@ pub enum Expr<'a> {
     Call(Call<'a>),
 
     Tag {
-        tag_layout: Layout<'a>,
+        tag_layout: UnionLayout<'a>,
         tag_name: TagName,
         tag_id: u8,
         union_size: u8,
@@ -3371,10 +3371,7 @@ pub fn with_hole<'a>(
                     Stmt::Let(
                         assigned,
                         expr,
-                        Layout::Builtin(Builtin::List(
-                            MemoryMode::Refcounted,
-                            env.arena.alloc(elem_layout),
-                        )),
+                        Layout::Builtin(Builtin::List(env.arena.alloc(elem_layout))),
                         hole,
                     )
                 }
@@ -3406,12 +3403,10 @@ pub fn with_hole<'a>(
                 elems: arg_symbols,
             };
 
-            let mode = MemoryMode::Refcounted;
-
             let stmt = Stmt::Let(
                 assigned,
                 expr,
-                Layout::Builtin(Builtin::List(mode, env.arena.alloc(elem_layout))),
+                Layout::Builtin(Builtin::List(env.arena.alloc(elem_layout))),
                 hole,
             );
 
@@ -4140,10 +4135,15 @@ fn construct_closure_data<'a>(
             tag_symbols.push(tag_id_symbol);
             tag_symbols.extend(symbols);
 
+            let tag_layout = match lambda_set.runtime_representation() {
+                Layout::Union(inner) => inner,
+                _ => unreachable!(),
+            };
+
             let expr1 = Expr::Literal(Literal::Int(tag_id as i128));
             let expr2 = Expr::Tag {
                 tag_id,
-                tag_layout: lambda_set.runtime_representation(),
+                tag_layout,
                 union_size,
                 tag_name,
                 arguments: tag_symbols.into_bump_slice(),
@@ -4305,17 +4305,17 @@ fn convert_tag_union<'a>(
                     }
 
                     debug_assert!(layouts.len() > 1);
-                    let layout = Layout::Union(UnionLayout::Recursive(layouts.into_bump_slice()));
+                    let union_layout = UnionLayout::Recursive(layouts.into_bump_slice());
 
                     let tag = Expr::Tag {
-                        tag_layout: layout,
+                        tag_layout: union_layout,
                         tag_name,
                         tag_id: tag_id as u8,
                         union_size,
                         arguments: field_symbols,
                     };
 
-                    (tag, layout)
+                    (tag, Layout::Union(union_layout))
                 }
                 NonNullableUnwrapped {
                     fields,
@@ -4333,17 +4333,17 @@ fn convert_tag_union<'a>(
                         temp.into_bump_slice()
                     };
 
-                    let layout = Layout::Union(UnionLayout::NonNullableUnwrapped(fields));
+                    let union_layout = UnionLayout::NonNullableUnwrapped(fields);
 
                     let tag = Expr::Tag {
-                        tag_layout: layout,
+                        tag_layout: union_layout,
                         tag_name,
                         tag_id: tag_id as u8,
                         union_size,
                         arguments: field_symbols,
                     };
 
-                    (tag, layout)
+                    (tag, Layout::Union(union_layout))
                 }
                 NonRecursive { sorted_tag_layouts } => {
                     let tag_id_symbol = env.unique_symbol();
@@ -4365,18 +4365,17 @@ fn convert_tag_union<'a>(
                         layouts.push(arg_layouts);
                     }
 
-                    let layout =
-                        Layout::Union(UnionLayout::NonRecursive(layouts.into_bump_slice()));
+                    let union_layout = UnionLayout::NonRecursive(layouts.into_bump_slice());
 
                     let tag = Expr::Tag {
-                        tag_layout: layout,
+                        tag_layout: union_layout,
                         tag_name,
                         tag_id: tag_id as u8,
                         union_size,
                         arguments: field_symbols,
                     };
 
-                    (tag, layout)
+                    (tag, Layout::Union(union_layout))
                 }
                 NullableWrapped {
                     nullable_id,
@@ -4402,20 +4401,20 @@ fn convert_tag_union<'a>(
                         layouts.push(arg_layouts);
                     }
 
-                    let layout = Layout::Union(UnionLayout::NullableWrapped {
+                    let union_layout = UnionLayout::NullableWrapped {
                         nullable_id,
                         other_tags: layouts.into_bump_slice(),
-                    });
+                    };
 
                     let tag = Expr::Tag {
-                        tag_layout: layout,
+                        tag_layout: union_layout,
                         tag_name,
                         tag_id: tag_id as u8,
                         union_size,
                         arguments: field_symbols,
                     };
 
-                    (tag, layout)
+                    (tag, Layout::Union(union_layout))
                 }
                 NullableUnwrapped {
                     nullable_id,
@@ -4437,20 +4436,20 @@ fn convert_tag_union<'a>(
                         temp.into_bump_slice()
                     };
 
-                    let layout = Layout::Union(UnionLayout::NullableUnwrapped {
+                    let union_layout = UnionLayout::NullableUnwrapped {
                         nullable_id,
                         other_fields,
-                    });
+                    };
 
                     let tag = Expr::Tag {
-                        tag_layout: layout,
+                        tag_layout: union_layout,
                         tag_name,
                         tag_id: tag_id as u8,
                         union_size,
                         arguments: field_symbols,
                     };
 
-                    (tag, layout)
+                    (tag, Layout::Union(union_layout))
                 }
             };
 
diff --git a/compiler/mono/src/layout.rs b/compiler/mono/src/layout.rs
index 7afa2efe28..e7af14e26e 100644
--- a/compiler/mono/src/layout.rs
+++ b/compiler/mono/src/layout.rs
@@ -40,24 +40,19 @@ pub enum Layout<'a> {
     /// A layout that is empty (turns into the empty struct in LLVM IR
     /// but for our purposes, not zero-sized, so it does not get dropped from data structures
     /// this is important for closures that capture zero-sized values
-    PhantomEmptyStruct,
     Struct(&'a [Layout<'a>]),
     Union(UnionLayout<'a>),
     RecursivePointer,
     /// A function. The types of its arguments, then the type of its return value.
     FunctionPointer(&'a [Layout<'a>], &'a Layout<'a>),
     Closure(&'a [Layout<'a>], LambdaSet<'a>, &'a Layout<'a>),
-    Pointer(&'a Layout<'a>),
 }
 
 impl<'a> Layout<'a> {
     pub fn in_place(&self) -> InPlace {
         match self {
             Layout::Builtin(Builtin::EmptyList) => InPlace::InPlace,
-            Layout::Builtin(Builtin::List(memory_mode, _)) => match memory_mode {
-                MemoryMode::Unique => InPlace::InPlace,
-                MemoryMode::Refcounted => InPlace::Clone,
-            },
+            Layout::Builtin(Builtin::List(_)) => InPlace::Clone,
             Layout::Builtin(Builtin::EmptyStr) => InPlace::InPlace,
             Layout::Builtin(Builtin::Str) => InPlace::Clone,
             Layout::Builtin(Builtin::Int1) => InPlace::Clone,
@@ -337,12 +332,6 @@ impl<'a> LambdaSet<'a> {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Copy)]
-pub enum MemoryMode {
-    Unique,
-    Refcounted,
-}
-
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub enum Builtin<'a> {
     Int128,
@@ -359,7 +348,7 @@ pub enum Builtin<'a> {
     Str,
     Dict(&'a Layout<'a>, &'a Layout<'a>),
     Set(&'a Layout<'a>),
-    List(MemoryMode, &'a Layout<'a>),
+    List(&'a Layout<'a>),
     EmptyStr,
     EmptyList,
     EmptyDict,
@@ -483,7 +472,6 @@ impl<'a> Layout<'a> {
 
         match self {
             Builtin(builtin) => builtin.safe_to_memcpy(),
-            PhantomEmptyStruct => true,
             Struct(fields) => fields
                 .iter()
                 .all(|field_layout| field_layout.safe_to_memcpy()),
@@ -508,10 +496,6 @@ impl<'a> Layout<'a> {
                 true
             }
             Closure(_, closure_layout, _) => closure_layout.safe_to_memcpy(),
-            Pointer(_) => {
-                // We cannot memcpy pointers, because then we would have the same pointer in multiple places!
-                false
-            }
             RecursivePointer => {
                 // We cannot memcpy pointers, because then we would have the same pointer in multiple places!
                 false
@@ -523,12 +507,7 @@ impl<'a> Layout<'a> {
         // For this calculation, we don't need an accurate
         // stack size, we just need to know whether it's zero,
         // so it's fine to use a pointer size of 1.
-        if let Layout::PhantomEmptyStruct = self {
-            false
-        } else {
-            // self.stack_size(1) == 0
-            false
-        }
+        false
     }
 
     pub fn stack_size(&self, pointer_size: u32) -> u32 {
@@ -536,7 +515,6 @@ impl<'a> Layout<'a> {
 
         match self {
             Builtin(builtin) => builtin.stack_size(pointer_size),
-            PhantomEmptyStruct => 0,
             Struct(fields) => {
                 let mut sum = 0;
 
@@ -570,7 +548,6 @@ impl<'a> Layout<'a> {
             Closure(_, lambda_set, _) => lambda_set.stack_size(pointer_size),
             FunctionPointer(_, _) => pointer_size,
             RecursivePointer => pointer_size,
-            Pointer(_) => pointer_size,
         }
     }
 
@@ -600,10 +577,8 @@ impl<'a> Layout<'a> {
                 }
             }
             Layout::Builtin(builtin) => builtin.alignment_bytes(pointer_size),
-            Layout::PhantomEmptyStruct => 0,
             Layout::RecursivePointer => pointer_size,
             Layout::FunctionPointer(_, _) => pointer_size,
-            Layout::Pointer(_) => pointer_size,
             Layout::Closure(_, captured, _) => {
                 pointer_size.max(captured.alignment_bytes(pointer_size))
             }
@@ -626,7 +601,7 @@ impl<'a> Layout<'a> {
 
             RecursivePointer => true,
 
-            Builtin(List(MemoryMode::Refcounted, _)) | Builtin(Str) => true,
+            Builtin(List(_)) | Builtin(Str) => true,
 
             _ => false,
         }
@@ -640,7 +615,6 @@ impl<'a> Layout<'a> {
 
         match self {
             Builtin(builtin) => builtin.is_refcounted(),
-            PhantomEmptyStruct => false,
             Struct(fields) => fields.iter().any(|f| f.contains_refcounted()),
             Union(variant) => {
                 use UnionLayout::*;
@@ -659,7 +633,7 @@ impl<'a> Layout<'a> {
             }
             RecursivePointer => true,
             Closure(_, closure_layout, _) => closure_layout.contains_refcounted(),
-            FunctionPointer(_, _) | Pointer(_) => false,
+            FunctionPointer(_, _) => false,
         }
     }
 
@@ -673,7 +647,6 @@ impl<'a> Layout<'a> {
 
         match self {
             Builtin(builtin) => builtin.to_doc(alloc, parens),
-            PhantomEmptyStruct => alloc.text("{}"),
             Struct(fields) => {
                 let fields_doc = fields.iter().map(|x| x.to_doc(alloc, parens));
 
@@ -706,7 +679,6 @@ impl<'a> Layout<'a> {
                     .append(" |} -> ")
                     .append(result.to_doc(alloc, Parens::InFunction))
             }
-            Pointer(_) => todo!(),
         }
     }
 }
@@ -878,7 +850,7 @@ impl<'a> Builtin<'a> {
             Str | EmptyStr => Builtin::STR_WORDS * pointer_size,
             Dict(_, _) | EmptyDict => Builtin::DICT_WORDS * pointer_size,
             Set(_) | EmptySet => Builtin::SET_WORDS * pointer_size,
-            List(_, _) | EmptyList => Builtin::LIST_WORDS * pointer_size,
+            List(_) | EmptyList => Builtin::LIST_WORDS * pointer_size,
         }
     }
 
@@ -904,7 +876,7 @@ impl<'a> Builtin<'a> {
             Str | EmptyStr => pointer_size,
             Dict(_, _) | EmptyDict => pointer_size,
             Set(_) | EmptySet => pointer_size,
-            List(_, _) | EmptyList => pointer_size,
+            List(_) | EmptyList => pointer_size,
         }
     }
 
@@ -914,7 +886,7 @@ impl<'a> Builtin<'a> {
         match self {
             Int128 | Int64 | Int32 | Int16 | Int8 | Int1 | Usize | Float128 | Float64 | Float32
             | Float16 | EmptyStr | EmptyDict | EmptyList | EmptySet => true,
-            Str | Dict(_, _) | Set(_) | List(_, _) => false,
+            Str | Dict(_, _) | Set(_) | List(_) => false,
         }
     }
 
@@ -925,10 +897,7 @@ impl<'a> Builtin<'a> {
         match self {
             Int128 | Int64 | Int32 | Int16 | Int8 | Int1 | Usize | Float128 | Float64 | Float32
             | Float16 | EmptyStr | EmptyDict | EmptyList | EmptySet => false,
-            List(mode, element_layout) => match mode {
-                MemoryMode::Refcounted => true,
-                MemoryMode::Unique => element_layout.contains_refcounted(),
-            },
+            List(_) => true,
 
             Str | Dict(_, _) | Set(_) => true,
         }
@@ -961,7 +930,7 @@ impl<'a> Builtin<'a> {
             EmptySet => alloc.text("EmptySet"),
 
             Str => alloc.text("Str"),
-            List(_, layout) => alloc
+            List(layout) => alloc
                 .text("List ")
                 .append(layout.to_doc(alloc, Parens::InTypeParam)),
             Set(layout) => alloc
@@ -1901,11 +1870,7 @@ pub fn list_layout_from_elem<'a>(
         _ => {
             let elem_layout = Layout::from_var(env, elem_var)?;
 
-            // This is a normal list.
-            Ok(Layout::Builtin(Builtin::List(
-                MemoryMode::Refcounted,
-                env.arena.alloc(elem_layout),
-            )))
+            Ok(Layout::Builtin(Builtin::List(env.arena.alloc(elem_layout))))
         }
     }
 }
@@ -1971,7 +1936,7 @@ impl<'a> std::convert::TryFrom<&Layout<'a>> for ListLayout<'a> {
     fn try_from(value: &Layout<'a>) -> Result<Self, Self::Error> {
         match value {
             Layout::Builtin(Builtin::EmptyList) => Ok(ListLayout::EmptyList),
-            Layout::Builtin(Builtin::List(_, element)) => Ok(ListLayout::List(element)),
+            Layout::Builtin(Builtin::List(element)) => Ok(ListLayout::List(element)),
             _ => Err(()),
         }
     }