diff --git a/compiler/builtins/src/bitcode.rs b/compiler/builtins/src/bitcode.rs
index e1a2a9f8f4..9321d08637 100644
--- a/compiler/builtins/src/bitcode.rs
+++ b/compiler/builtins/src/bitcode.rs
@@ -1,4 +1,5 @@
 use roc_module::symbol::Symbol;
+use roc_target::TargetInfo;
 use std::ops::Index;
 
 pub const BUILTINS_HOST_OBJ_PATH: &str = env!(
@@ -46,7 +47,7 @@ impl FloatWidth {
         }
     }
 
-    pub const fn alignment_bytes(&self) -> u32 {
+    pub const fn alignment_bytes(&self, target_info: TargetInfo) -> u32 {
         use std::mem::align_of;
         use FloatWidth::*;
 
@@ -106,11 +107,10 @@ impl IntWidth {
         }
     }
 
-    pub const fn alignment_bytes(&self) -> u32 {
+    pub const fn alignment_bytes(&self, target_info: TargetInfo) -> u32 {
         use std::mem::align_of;
         use IntWidth::*;
 
-        // TODO actually alignment is architecture-specific
         match self {
             U8 | I8 => align_of::<i8>() as u32,
             U16 | I16 => align_of::<i16>() as u32,
diff --git a/compiler/mono/src/layout.rs b/compiler/mono/src/layout.rs
index 12d759f8b8..2055b03fd2 100644
--- a/compiler/mono/src/layout.rs
+++ b/compiler/mono/src/layout.rs
@@ -1341,10 +1341,10 @@ impl<'a> Builtin<'a> {
         // since both of those are one pointer size, the alignment of that structure is a pointer
         // size
         match self {
-            Int(int_width) => int_width.alignment_bytes(),
-            Float(float_width) => float_width.alignment_bytes(),
+            Int(int_width) => int_width.alignment_bytes(target_info),
+            Float(float_width) => float_width.alignment_bytes(target_info),
             Bool => align_of::<bool>() as u32,
-            Decimal => IntWidth::I128.alignment_bytes(),
+            Decimal => IntWidth::I128.alignment_bytes(target_info),
             Dict(_, _) => ptr_width,
             Set(_) => ptr_width,
             // we often treat these as i128 (64-bit systems)
diff --git a/compiler/mono/src/layout_soa.rs b/compiler/mono/src/layout_soa.rs
index 1481b38723..fe37cc385d 100644
--- a/compiler/mono/src/layout_soa.rs
+++ b/compiler/mono/src/layout_soa.rs
@@ -3,6 +3,7 @@ use roc_builtins::bitcode::{FloatWidth, IntWidth};
 use roc_collections::all::MutMap;
 use roc_module::ident::TagName;
 use roc_module::symbol::Symbol;
+use roc_target::TargetInfo;
 use roc_types::subs::{Content, FlatType, Subs, Variable};
 use roc_types::types::RecordField;
 use std::collections::hash_map::Entry;
@@ -99,7 +100,7 @@ pub struct Layouts {
     lambda_sets: Vec<LambdaSet>,
     symbols: Vec<Symbol>,
     recursion_variable_to_structure_variable_map: MutMap<Variable, Index<Layout>>,
-    usize_int_width: IntWidth,
+    target_info: TargetInfo,
 }
 
 pub struct FunctionLayout {
@@ -402,7 +403,7 @@ impl Layouts {
     const VOID_TUPLE: Index<(Layout, Layout)> = Index::new(0);
     const UNIT_INDEX: Index<Layout> = Index::new(2);
 
-    pub fn new(usize_int_width: IntWidth) -> Self {
+    pub fn new(target_info: TargetInfo) -> Self {
         let mut layouts = Vec::with_capacity(64);
 
         layouts.push(Layout::VOID);
@@ -420,7 +421,7 @@ impl Layouts {
             lambda_sets: Vec::default(),
             symbols: Vec::default(),
             recursion_variable_to_structure_variable_map: MutMap::default(),
-            usize_int_width,
+            target_info,
         }
     }
 
@@ -443,7 +444,12 @@ impl Layouts {
     }
 
     fn usize(&self) -> Layout {
-        Layout::Int(self.usize_int_width)
+        let usize_int_width = match self.target_info.ptr_width() {
+            roc_target::PtrWidth::Bytes4 => IntWidth::U32,
+            roc_target::PtrWidth::Bytes8 => IntWidth::U64,
+        };
+
+        Layout::Int(usize_int_width)
     }
 
     fn align_of_layout_index(&self, index: Index<Layout>) -> u16 {
@@ -453,18 +459,23 @@ impl Layouts {
     }
 
     fn align_of_layout(&self, layout: Layout) -> u16 {
-        let ptr_alignment = self.usize_int_width.alignment_bytes() as u16;
+        let usize_int_width = match self.target_info.ptr_width() {
+            roc_target::PtrWidth::Bytes4 => IntWidth::U32,
+            roc_target::PtrWidth::Bytes8 => IntWidth::U64,
+        };
+
+        let ptr_alignment = usize_int_width.alignment_bytes(self.target_info) as u16;
 
         match layout {
             Layout::Reserved => unreachable!(),
-            Layout::Int(int_width) => int_width.alignment_bytes() as u16,
-            Layout::Float(float_width) => float_width.alignment_bytes() as u16,
-            Layout::Decimal => IntWidth::U128.alignment_bytes() as u16,
+            Layout::Int(int_width) => int_width.alignment_bytes(self.target_info) as u16,
+            Layout::Float(float_width) => float_width.alignment_bytes(self.target_info) as u16,
+            Layout::Decimal => IntWidth::U128.alignment_bytes(self.target_info) as u16,
             Layout::Str | Layout::Dict(_) | Layout::Set(_) | Layout::List(_) => ptr_alignment,
             Layout::Struct(slice) => self.align_of_layout_slice(slice),
             Layout::Boxed(_) | Layout::UnionRecursive(_) => ptr_alignment,
             Layout::UnionNonRecursive(slices) => {
-                let tag_id_align = IntWidth::I64.alignment_bytes() as u16;
+                let tag_id_align = IntWidth::I64.alignment_bytes(self.target_info) as u16;
 
                 self.align_of_layout_slices(slices).max(tag_id_align)
             }
@@ -518,7 +529,12 @@ impl Layouts {
     }
 
     pub fn size_of_layout(&self, layout: Layout) -> u16 {
-        let ptr_width = self.usize_int_width.stack_size() as u16;
+        let usize_int_width = match self.target_info.ptr_width() {
+            roc_target::PtrWidth::Bytes4 => IntWidth::U32,
+            roc_target::PtrWidth::Bytes8 => IntWidth::U64,
+        };
+
+        let ptr_width = usize_int_width.stack_size() as u16;
 
         match layout {
             Layout::Reserved => unreachable!(),