diff --git a/compiler/gen/src/llvm/build.rs b/compiler/gen/src/llvm/build.rs
index 74e5348653..9571783bc5 100644
--- a/compiler/gen/src/llvm/build.rs
+++ b/compiler/gen/src/llvm/build.rs
@@ -1395,23 +1395,122 @@ pub fn build_exp_stmt<'a, 'ctx, 'env>(
 
             env.builder.build_store(alloca, val);
 
-            // Make a new scope which includes the binding we just encountered.
-            // This should be done *after* compiling the bound expr, since any
-            // recursive (in the LetRec sense) bindings should already have
-            // been extracted as procedures. Nothing in here should need to
-            // access itself!
-            // scope = scope.clone();
+            let arguments = call.arguments;
+            match call.call_type {
+                CallType::ByName {
+                    name,
+                    ref full_layout,
+                    ..
+                } => {
+                    let function_value = function_value_by_name(env, layout_ids, full_layout, name);
 
-            let pass_branch = {
-                scope.insert(*symbol, (layout.clone(), alloca));
+                    let mut arg_vals: Vec<BasicValueEnum> =
+                        Vec::with_capacity_in(arguments.len(), env.arena);
 
-                let result = build_exp_stmt(env, layout_ids, scope, parent, pass);
+                    for arg in arguments.iter() {
+                        arg_vals.push(load_symbol(env, scope, arg));
+                    }
 
-                scope.remove(symbol);
-                result
-            };
+                    let pass_block = context.append_basic_block(parent, "invoke_pass");
+                    let fail_block = context.append_basic_block(parent, "invoke_fail");
 
-            pass_branch
+                    {
+                        env.builder.position_at_end(pass_block);
+
+                        scope.insert(*symbol, (layout.clone(), alloca));
+
+                        build_exp_stmt(env, layout_ids, scope, parent, pass);
+
+                        scope.remove(symbol);
+                    }
+
+                    {
+                        env.builder.position_at_end(fail_block);
+
+                        build_exp_stmt(env, layout_ids, scope, parent, fail);
+                    }
+
+                    let call = env.builder.build_invoke(
+                        function_value,
+                        arg_vals.as_slice(),
+                        pass_block,
+                        fail_block,
+                        "tmp",
+                    );
+
+                    if env.exposed_to_host.contains(&name) {
+                        // If this is an external-facing function, use the C calling convention.
+                        call.set_call_convention(C_CALL_CONV);
+                    } else {
+                        // If it's an internal-only function, use the fast calling convention.
+                        call.set_call_convention(FAST_CALL_CONV);
+                    }
+
+                    call.try_as_basic_value()
+                        .left()
+                        .unwrap_or_else(|| panic!("LLVM error: Invalid call by pointer."))
+                }
+                CallType::ByPointer { name, .. } => {
+                    let sub_expr = load_symbol(env, scope, &name);
+
+                    let mut arg_vals: Vec<BasicValueEnum> =
+                        Vec::with_capacity_in(arguments.len(), env.arena);
+
+                    for arg in arguments.iter() {
+                        arg_vals.push(load_symbol(env, scope, arg));
+                    }
+
+                    let pass_block = context.append_basic_block(parent, "invoke_pass");
+                    let fail_block = context.append_basic_block(parent, "invoke_fail");
+
+                    {
+                        env.builder.position_at_end(pass_block);
+
+                        scope.insert(*symbol, (layout.clone(), alloca));
+
+                        build_exp_stmt(env, layout_ids, scope, parent, pass);
+
+                        scope.remove(symbol);
+                    }
+
+                    {
+                        env.builder.position_at_end(fail_block);
+
+                        build_exp_stmt(env, layout_ids, scope, parent, fail);
+                    }
+
+                    let call = match sub_expr {
+                        BasicValueEnum::PointerValue(ptr) => env.builder.build_invoke(
+                            ptr,
+                            arg_vals.as_slice(),
+                            pass_block,
+                            fail_block,
+                            "tmp",
+                        ),
+                        non_ptr => {
+                            panic!(
+                                "Tried to call by pointer, but encountered a non-pointer: {:?}",
+                                non_ptr
+                            );
+                        }
+                    };
+
+                    if env.exposed_to_host.contains(&name) {
+                        // If this is an external-facing function, use the C calling convention.
+                        call.set_call_convention(C_CALL_CONV);
+                    } else {
+                        // If it's an internal-only function, use the fast calling convention.
+                        call.set_call_convention(FAST_CALL_CONV);
+                    }
+
+                    call.try_as_basic_value()
+                        .left()
+                        .unwrap_or_else(|| panic!("LLVM error: Invalid call by pointer."))
+                }
+                _ => {
+                    todo!()
+                }
+            }
         }
 
         Unreachable => {
@@ -2579,6 +2678,29 @@ pub fn verify_fn(fn_val: FunctionValue<'_>) {
     }
 }
 
+fn function_value_by_name<'a, 'ctx, 'env>(
+    env: &Env<'a, 'ctx, 'env>,
+    layout_ids: &mut LayoutIds<'a>,
+    layout: &Layout<'a>,
+    symbol: Symbol,
+) -> FunctionValue<'ctx> {
+    let fn_name = layout_ids
+        .get(symbol, layout)
+        .to_symbol_string(symbol, &env.interns);
+    let fn_name = fn_name.as_str();
+
+    env.module.get_function(fn_name).unwrap_or_else(|| {
+        if symbol.is_builtin() {
+            panic!("Unrecognized builtin function: {:?}", fn_name)
+        } else {
+            panic!(
+                "Unrecognized non-builtin function: {:?} (symbol: {:?}, layout: {:?})",
+                fn_name, symbol, layout
+            )
+        }
+    })
+}
+
 // #[allow(clippy::cognitive_complexity)]
 #[inline(always)]
 fn call_with_args<'a, 'ctx, 'env>(
@@ -2589,21 +2711,7 @@ fn call_with_args<'a, 'ctx, 'env>(
     _parent: FunctionValue<'ctx>,
     args: &[BasicValueEnum<'ctx>],
 ) -> BasicValueEnum<'ctx> {
-    let fn_name = layout_ids
-        .get(symbol, layout)
-        .to_symbol_string(symbol, &env.interns);
-    let fn_name = fn_name.as_str();
-
-    let fn_val = env.module.get_function(fn_name).unwrap_or_else(|| {
-        if symbol.is_builtin() {
-            panic!("Unrecognized builtin function: {:?}", fn_name)
-        } else {
-            panic!(
-                "Unrecognized non-builtin function: {:?} (symbol: {:?}, layout: {:?})",
-                fn_name, symbol, layout
-            )
-        }
-    });
+    let fn_val = function_value_by_name(env, layout_ids, layout, symbol);
 
     let call = env.builder.build_call(fn_val, args, "call");