diff --git a/src/compiler.bbb b/src/compiler.bbb
index 1cc3587..cf68319 100644
--- a/src/compiler.bbb
+++ b/src/compiler.bbb
@@ -823,14 +823,21 @@ MacroInstantiation = struct
 
 LLVMContext = opaque;
 LLVMModule = opaque;
+
 LLVMBuilder = opaque;
-LLVMDIBuilder = opaque;
+
 LLVMValue = opaque;
 LLVMType = opaque;
-LLVMMetadata = opaque;
 LLVMBasicBlock = opaque;
 LLVMIntrinsicId = typealias u32;
 
+LLVMMetadata = opaque;
+LLVMDIBuilder = opaque;
+
+LLVMTarget = opaque;
+LLVMTargetMachine = opaque;
+LLVMTargetMachineOptions = opaque;
+
 LLVMIntrinsicIndex = enum
 {
     trap,
@@ -887,6 +894,13 @@ LLVMCodeGenerationOptimizationLevel = enum
 [extern] llvm_context_create_module = fn (context: &LLVMContext, name: []u8) &LLVMModule;
 [extern] LLVMCreateBuilderInContext = fn (context: &LLVMContext) &LLVMBuilder;
 
+[extern] LLVMCreateTargetMachineOptions = fn () &LLVMTargetMachineOptions;
+[extern] LLVMTargetMachineOptionsSetCPU = fn (target_machine_options: &LLVMTargetMachineOptions, cpu: &u8) void;
+[extern] LLVMTargetMachineOptionsSetFeatures = fn (target_machine_options: &LLVMTargetMachineOptions, features: &u8) void;
+[extern] LLVMTargetMachineOptionsSetCodeGenOptLevel = fn (target_machine_options: &LLVMTargetMachineOptions, optimization_level: LLVMCodeGenerationOptimizationLevel) void;
+[extern] LLVMGetTargetFromTriple = fn (target_triple: &u8, target_pointer: &&LLVMTarget, error_message_pointer: &&u8) s32;
+[extern] LLVMCreateTargetMachineWithOptions = fn (target: &LLVMTarget, target_triple: &u8, target_machine_options: &LLVMTargetMachineOptions) &LLVMTargetMachine;
+
 ModuleLLVM = struct
 {
     context: &LLVMContext,
@@ -2690,6 +2704,10 @@ emit = fn (module: &Module) void
         #trap();
     }
 
+    >target_machine_options = LLVMCreateTargetMachineOptions();
+    LLVMTargetMachineOptionsSetCPU(target_machine_options, cpu_model.pointer);
+    LLVMTargetMachineOptionsSetFeatures(target_machine_options, cpu_features.pointer);
+
     >code_generation_optimization_level: LLVMCodeGenerationOptimizationLevel = undefined;
     switch (module.build_mode)
     {
@@ -2698,6 +2716,20 @@ emit = fn (module: &Module) void
         .optimize_for_speed, .optimize_for_size => { code_generation_optimization_level = .default; },
         .aggressively_optimize_for_speed, .aggressively_optimize_for_size => { code_generation_optimization_level = .aggressive; },
     }
+
+    LLVMTargetMachineOptionsSetCodeGenOptLevel(target_machine_options, code_generation_optimization_level);
+
+    >target: &LLVMTarget = zero;
+    >error_message: &u8 = zero;
+    >result = LLVMGetTargetFromTriple(target_triple.pointer, &target, &error_message);
+    if (result != 0)
+    {
+        report_error();
+    }
+
+    assert(!error_message);
+
+    LLVMCreateTargetMachineWithOptions(target, target_triple.pointer, target_machine_options);
 }
 
 compile = fn (arena: &Arena, options: CompileOptions) void
diff --git a/src/compiler.cpp b/src/compiler.cpp
index 88080c0..0df0659 100644
--- a/src/compiler.cpp
+++ b/src/compiler.cpp
@@ -434,6 +434,7 @@ global_variable String names[] =
     string_literal("enum_array"),
     string_literal("opaque"),
     string_literal("basic_struct_passing"),
+    string_literal("enum_arbitrary_abi"),
 };
 
 void entry_point(Slice<char* const> arguments, Slice<char* const> envp)
diff --git a/src/emitter.cpp b/src/emitter.cpp
index bfd834e..656b7ef 100644
--- a/src/emitter.cpp
+++ b/src/emitter.cpp
@@ -4862,7 +4862,7 @@ fn LLVMValueRef emit_call(Module* module, Value* value, LLVMValueRef left_llvm,
 
                                 if (coerce_to_type->id != TypeId::structure && type_is_abi_equal(module, semantic_argument_type, coerce_to_type) && argument_abi.attributes.direct.offset == 0)
                                 {
-                                    emit_value(module, semantic_call_argument_value, TypeKind::memory, false);
+                                    emit_value(module, semantic_call_argument_value, TypeKind::abi, false);
 
                                     auto evaluation_kind = get_evaluation_kind(argument_abi.semantic_type);
                                     Value* v;
diff --git a/src/llvm.cpp b/src/llvm.cpp
index c6243b8..fd6b78d 100644
--- a/src/llvm.cpp
+++ b/src/llvm.cpp
@@ -879,8 +879,9 @@ EXPORT String llvm_default_target_triple()
     u8* pointer = 0;
     if (length)
     {
-        pointer = new u8[length];
+        pointer = new u8[length + 1];
         memcpy(pointer, triple.c_str(), length);
+        pointer[length] = 0;
     }
 
     return { pointer, length };
@@ -889,7 +890,9 @@ EXPORT String llvm_default_target_triple()
 EXPORT String llvm_host_cpu_name()
 {
     auto cpu = llvm::sys::getHostCPUName();
-    return { (u8*)cpu.data(), cpu.size() };
+    auto result = String { (u8*)cpu.data(), cpu.size() };
+    assert(result.pointer[result.length] == 0);
+    return result;
 }
 
 EXPORT String llvm_host_cpu_features()
@@ -916,7 +919,8 @@ EXPORT String llvm_host_cpu_features()
     if (length)
     {
         result = new u8[length];
-        memcpy(result, feature_string.c_str(), length);
+        memcpy(result, feature_string.c_str(), length + 1);
+        result[length] = 0;
     }
 
     return { result, length };
diff --git a/tests/enum_arbitrary_abi.bbb b/tests/enum_arbitrary_abi.bbb
new file mode 100644
index 0000000..e98d1b7
--- /dev/null
+++ b/tests/enum_arbitrary_abi.bbb
@@ -0,0 +1,22 @@
+SomeEnum = enum
+{
+    a,
+    b,
+    c,
+    d,
+}
+
+foo = fn (arg: SomeEnum) SomeEnum
+{
+    return arg;
+}
+
+[export] main = fn [cc(c)] () s32
+{
+    >some_e: SomeEnum = .c;
+    >a = foo(some_e);
+    >b = foo(.d);
+    if (a != .c) #trap();
+    if (b != .d) #trap();
+    return 0;
+}