diff --git a/CMakeLists.txt b/CMakeLists.txt
index c4ae5d92e..e08a44d6a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,6 +9,7 @@ set(C3_LLVM_VERSION "auto" CACHE STRING "Use LLVM version [default: auto]")
 option(C3_USE_MIMALLOC "Use built-in mimalloc" OFF)
 set(C3_MIMALLOC_TAG "v1.7.3" CACHE STRING "Used version of mimalloc")
 
+set(C3_USE_MIMALLOC OFF)
 if(C3_USE_MIMALLOC)
     option(MI_BUILD_TESTS OFF)
     option(MI_BUILD_SHARED OFF)
@@ -180,7 +181,6 @@ add_executable(c3c
         src/compiler/tokens.c
         src/compiler/types.c
         src/main.c
-        src/target_info/target_info.c
         src/utils/errors.c
         src/utils/file_utils.c
         src/utils/find_msvc.c
diff --git a/src/build/build_options.c b/src/build/build_options.c
index d8224a4c4..cac087060 100644
--- a/src/build/build_options.c
+++ b/src/build/build_options.c
@@ -389,6 +389,22 @@ static void parse_option(BuildOptions *options)
 				FAIL_WITH_ERR("Invalid optimization level.");
 			}
 			return;
+		case 'm':
+			if (match_shortopt("mno-avx"))
+			{
+				options->no_avx = true;
+			} else if (match_shortopt("mavx"))
+			{
+				options->avx = true;
+			} else if (match_shortopt("mavx512"))
+			{
+				options->avx512 = true;
+			}
+			else
+			{
+				FAIL_WITH_ERR("Invalid -m option.");
+			}
+			return;
 		case 'E':
 			if (options->compile_option != COMPILE_NORMAL)
 			{
diff --git a/src/build/build_options.h b/src/build/build_options.h
index e34a4527f..7ea40d205 100644
--- a/src/build/build_options.h
+++ b/src/build/build_options.h
@@ -204,6 +204,9 @@ typedef struct BuildOptions_
 	bool emit_bitcode;
 	bool test_mode;
 	bool no_stdlib;
+	bool no_avx;
+	bool avx;
+	bool avx512;
 } BuildOptions;
 
 
@@ -262,6 +265,8 @@ typedef struct
 		bool no_sse : 1;
 		bool no_mmx : 1;
 		bool no_avx : 1;
+		bool avx : 1;
+		bool avx512 : 1;
 	} feature;
 } BuildTarget;
 
diff --git a/src/build/builder.c b/src/build/builder.c
index 690c4e413..9ee8465af 100644
--- a/src/build/builder.c
+++ b/src/build/builder.c
@@ -117,6 +117,9 @@ static void update_build_target_from_options(BuildTarget *target, BuildOptions *
 	}
 	target->no_stdlib = options->no_stdlib;
 	target->emit_llvm = options->emit_llvm;
+	if (options->no_avx) target->feature.no_avx = true;
+	if (options->avx) target->feature.avx = true;
+	if (options->avx512) target->feature.avx512 = true;
 	switch (options->compile_option)
 	{
 		case COMPILE_NORMAL:
diff --git a/src/build/project.c b/src/build/project.c
index 9bfd22073..380a0cac3 100644
--- a/src/build/project.c
+++ b/src/build/project.c
@@ -201,6 +201,8 @@ void project_add_target(Project *project, TomlValue *wrapped_table, const char *
 	// Use the fact that they correspond to 0, 1, -1
 	target->feature.struct_return = get_valid_bool(table, "stack-struct-return", type, STRUCT_RETURN_DEFAULT);
 	target->feature.soft_float = get_valid_bool(table, "soft-float", type, SOFT_FLOAT_DEFAULT);
+	target->feature.avx = get_valid_bool(table, "avx", type, false);
+	target->feature.avx512 = get_valid_bool(table, "avx512", type, false);
 	target->feature.no_avx = get_valid_bool(table, "no-avx", type, false);
 	target->feature.no_sse = get_valid_bool(table, "no-sse", type, false);
 	target->feature.no_mmx = get_valid_bool(table, "no-mmx", type, false);
diff --git a/src/compiler/compiler_internal.h b/src/compiler/compiler_internal.h
index 4c176bc74..57f4639b6 100644
--- a/src/compiler/compiler_internal.h
+++ b/src/compiler/compiler_internal.h
@@ -1561,11 +1561,13 @@ typedef struct FunctionPrototype_
 	bool ret_by_ref : 1;
 	Type *rtype;
 	Type **params;
+	Type **varargs;
 	Type *ret_by_ref_type;
 	Type *abi_ret_type;
 	ABIArgInfo *ret_abi_info;
 	ABIArgInfo *ret_by_ref_abi_info;
 	ABIArgInfo **abi_args;
+	ABIArgInfo **abi_varargs;
 	void *tb_prototype;
 } FunctionPrototype;
 
@@ -2050,6 +2052,7 @@ void *llvm_target_machine_create(void);
 void target_setup(BuildTarget *build_target);
 int target_alloca_addr_space();
 
+void c_abi_func_create(FunctionPrototype *proto);
 
 bool token_is_type(TokenType type);
 bool token_is_any_type(TokenType type);
diff --git a/src/compiler/llvm_codegen_c_abi_x64.c b/src/compiler/llvm_codegen_c_abi_x64.c
index 5ad0ec2e2..c4b00e0af 100644
--- a/src/compiler/llvm_codegen_c_abi_x64.c
+++ b/src/compiler/llvm_codegen_c_abi_x64.c
@@ -359,7 +359,7 @@ void x64_classify_vector(Type *type, ByteSize offset_base, X64Class *current, X6
 		}
 		return;
 	}
-	if (size == 16 || named_arg || size <= x64_native_vector_size_for_avx())
+	if (size == 16 || (named_arg == NAMED && size <= x64_native_vector_size_for_avx()))
 	{
 		if (platform_target.x64.pass_int128_vector_in_mem) return;
 
@@ -921,4 +921,15 @@ void c_abi_func_create_x64(FunctionPrototype *prototype)
 		}
 		prototype->abi_args = args;
 	}
+	unsigned vararg_count = vec_size(prototype->varargs);
+	if (vararg_count)
+	{
+		ABIArgInfo **args = MALLOC(sizeof(ABIArgInfo) * vararg_count);
+		for (unsigned i = 0; i < vararg_count; i++)
+		{
+			args[i] = x64_classify_parameter(prototype->varargs[i], &available_registers, is_regcall, UNNAMED);
+		}
+		prototype->abi_varargs = args;
+	}
+
 }
diff --git a/src/compiler/llvm_codegen_expr.c b/src/compiler/llvm_codegen_expr.c
index b2bea509f..4df3cb261 100644
--- a/src/compiler/llvm_codegen_expr.c
+++ b/src/compiler/llvm_codegen_expr.c
@@ -789,6 +789,7 @@ static inline void llvm_extract_bitvalue_from_array(GenContext *c, BEValue *be_v
 			res = element;
 			continue;
 		}
+
 		res = LLVMBuildOr(c->builder, element, res, "");
 	}
 	if (big_endian)
@@ -4331,6 +4332,31 @@ void llvm_emit_builtin_call(GenContext *c, BEValue *result_value, Expr *expr)
 	llvm_emit_intrinsic_expr(c, llvm_get_intrinsic(func), result_value, expr);
 }
 
+void llvm_add_call_attributes(GenContext *c, LLVMValueRef call_value, int start_index, int count, Type **types, ABIArgInfo **infos)
+{
+	for (unsigned i = 0; i < count; i++)
+	{
+		Type *param = types[i];
+		ABIArgInfo *info = infos[i];
+		switch (info->kind)
+		{
+			case ABI_ARG_INDIRECT:
+				if (info->attributes.by_val)
+				{
+					llvm_attribute_add_call_type(c,
+					                             call_value,
+					                             attribute_id.byval,
+					                             (int)i + start_index,
+					                             llvm_get_type(c, info->indirect.type));
+				}
+				llvm_attribute_add_call(c, call_value, attribute_id.align, (int)i + start_index, info->indirect.alignment);
+				break;
+			default:
+				break;
+		}
+	}
+
+}
 void llvm_emit_call_expr(GenContext *c, BEValue *result_value, Expr *expr)
 {
 	if (expr->call_expr.is_builtin)
@@ -4385,7 +4411,28 @@ void llvm_emit_call_expr(GenContext *c, BEValue *result_value, Expr *expr)
 	ABIArgInfo **abi_args = prototype->abi_args;
 	unsigned param_count = vec_size(params);
 	unsigned non_variadic_params = param_count;
+	Expr **args = expr->call_expr.arguments;
+	unsigned arguments = vec_size(args);
+
 	if (prototype->variadic == VARIADIC_TYPED) non_variadic_params--;
+	FunctionPrototype copy;
+	if (prototype->variadic == VARIADIC_RAW)
+	{
+		if (arguments > non_variadic_params)
+		{
+			copy = *prototype;
+			copy.varargs = NULL;
+			for (unsigned i = non_variadic_params; i < arguments; i++)
+			{
+				vec_add(copy.varargs, args[i]->type);
+			}
+			copy.ret_abi_info = NULL;
+			copy.ret_by_ref_abi_info = NULL;
+			copy.abi_args = NULL;
+			c_abi_func_create(&copy);
+			prototype = &copy;
+		}
+	}
 	ABIArgInfo *ret_info = prototype->ret_abi_info;
 	Type *call_return_type = prototype->abi_ret_type;
 
@@ -4442,12 +4489,11 @@ void llvm_emit_call_expr(GenContext *c, BEValue *result_value, Expr *expr)
 
 
 	// 8. Add all other arguments.
-	unsigned arguments = vec_size(expr->call_expr.arguments);
 	assert(arguments >= non_variadic_params);
 	for (unsigned i = 0; i < non_variadic_params; i++)
 	{
 		// 8a. Evaluate the expression.
-		Expr *arg_expr = expr->call_expr.arguments[i];
+		Expr *arg_expr = args[i];
 		llvm_emit_expr(c, &temp_value, arg_expr);
 
 		// 8b. Emit the parameter according to ABI rules.
@@ -4508,13 +4554,30 @@ void llvm_emit_call_expr(GenContext *c, BEValue *result_value, Expr *expr)
 	}
 	else
 	{
-		// 9. Emit varargs.
-		for (unsigned i = param_count; i < arguments; i++)
+		if (prototype->abi_varargs)
 		{
-			Expr *arg_expr = expr->call_expr.arguments[i];
-			llvm_emit_expr(c, &temp_value, arg_expr);
-			REMINDER("Varargs should be expanded correctly");
-			vec_add(values, llvm_load_value_store(c, &temp_value));
+			// 9. Emit varargs.
+			unsigned index = 0;
+			ABIArgInfo **abi_varargs = prototype->abi_varargs;
+			for (unsigned i = param_count; i < arguments; i++)
+			{
+				Expr *arg_expr = args[i];
+				llvm_emit_expr(c, &temp_value, arg_expr);
+				ABIArgInfo *info = abi_varargs[index];
+				llvm_emit_parameter(c, &values, info, &temp_value, prototype->varargs[index]);
+				index++;
+			}
+		}
+		else
+		{
+			// 9. Emit varargs.
+			for (unsigned i = param_count; i < arguments; i++)
+			{
+				Expr *arg_expr = args[i];
+				llvm_emit_expr(c, &temp_value, arg_expr);
+				REMINDER("Varargs should be expanded correctly");
+				vec_add(values, llvm_load_value_store(c, &temp_value));
+			}
 		}
 	}
 
@@ -4538,22 +4601,10 @@ void llvm_emit_call_expr(GenContext *c, BEValue *result_value, Expr *expr)
 		}
 	}
 
-	for (unsigned i = 0; i < non_variadic_params; i++)
+	llvm_add_call_attributes(c, call_value, 1, non_variadic_params, params, abi_args);
+	if (prototype->abi_varargs)
 	{
-		Type *param = params[i];
-		ABIArgInfo *info = abi_args[i];
-		switch (info->kind)
-		{
-			case ABI_ARG_INDIRECT:
-				if (info->attributes.by_val)
-				{
-					llvm_attribute_add_call_type(c, call_value, attribute_id.byval, (int)i + 1, llvm_get_type(c, info->indirect.type));
-				}
-				llvm_attribute_add_call(c, call_value, attribute_id.align, (int)i + 1, info->indirect.alignment);
-				break;
-			default:
-				break;
-		}
+		llvm_add_call_attributes(c, call_value, 1 + non_variadic_params, vec_size(prototype->varargs), prototype->varargs, prototype->abi_varargs);
 	}
 
 	// 11. Process the return value.
diff --git a/src/compiler/llvm_codegen_internal.h b/src/compiler/llvm_codegen_internal.h
index 839aca4b0..f521442a6 100644
--- a/src/compiler/llvm_codegen_internal.h
+++ b/src/compiler/llvm_codegen_internal.h
@@ -217,7 +217,6 @@ void llvm_value_set_decl(BEValue *value, Decl *decl);
 void llvm_value_fold_failable(GenContext *c, BEValue *value);
 void llvm_value_struct_gep(GenContext *c, BEValue *element, BEValue *struct_pointer, unsigned index);
 
-
 LLVMTypeRef llvm_abi_type(GenContext *c, AbiType type);
 TypeSize llvm_abi_size(GenContext *c, LLVMTypeRef type);
 BitSize llvm_bitsize(GenContext *c, LLVMTypeRef type);
@@ -269,6 +268,8 @@ void llvm_emit_int_comparison(GenContext *c, BEValue *result, BEValue *lhs, BEVa
 void llvm_emit_int_comp(GenContext *c, BEValue *result, Type *lhs_type, Type *rhs_type, LLVMValueRef lhs_value, LLVMValueRef rhs_value, BinaryOp binary_op);
 void llvm_emit_comparison(GenContext *c, BEValue *be_value, BEValue *lhs, BEValue *rhs, BinaryOp binary_op);
 void llvm_emit_len_for_expr(GenContext *c, BEValue *be_value, BEValue *expr_to_len);
+// -- type ---
+LLVMTypeRef llvm_func_type(GenContext *context, FunctionPrototype *prototype);
 
 // -- instr ---
 void llvm_emit_cond_br(GenContext *context, BEValue *value, LLVMBasicBlockRef then_block, LLVMBasicBlockRef else_block);
diff --git a/src/compiler/llvm_codegen_type.c b/src/compiler/llvm_codegen_type.c
index 883601f5c..749c67115 100644
--- a/src/compiler/llvm_codegen_type.c
+++ b/src/compiler/llvm_codegen_type.c
@@ -217,10 +217,9 @@ static inline void add_func_type_param(GenContext *context, Type *param_type, AB
 	arg_info->param_index_end = (MemberIndex)vec_size(*params);
 }
 
-LLVMTypeRef llvm_func_type(GenContext *context, Type *type)
+LLVMTypeRef llvm_func_type(GenContext *context, FunctionPrototype *prototype)
 {
 	LLVMTypeRef *params = NULL;
-	FunctionPrototype *prototype = type->func.prototype;
 
 	LLVMTypeRef return_type = NULL;
 
@@ -282,6 +281,11 @@ LLVMTypeRef llvm_func_type(GenContext *context, Type *type)
 		add_func_type_param(context, prototype->params[i], prototype->abi_args[i], &params);
 	}
 
+	VECEACH(prototype->varargs, i)
+	{
+		add_func_type_param(context, prototype->varargs[i], prototype->abi_varargs[i], &params);
+	}
+
 	return LLVMFunctionType(return_type, params, vec_size(params), prototype->variadic == VARIADIC_RAW);
 }
 
@@ -324,7 +328,7 @@ LLVMTypeRef llvm_get_type(GenContext *c, Type *any_type)
 		case TYPE_BITSTRUCT:
 			return any_type->backend_type = llvm_type_from_decl(c, any_type->decl);
 		case TYPE_FUNC:
-			return any_type->backend_type = llvm_func_type(c, any_type);
+			return any_type->backend_type = llvm_func_type(c, any_type->func.prototype);
 		case TYPE_VOID:
 			return any_type->backend_type = LLVMVoidTypeInContext(c->context);
 		case TYPE_F64:
diff --git a/src/compiler/target.c b/src/compiler/target.c
index c1a2103fc..fae4d92fd 100644
--- a/src/compiler/target.c
+++ b/src/compiler/target.c
@@ -1,7 +1,6 @@
 #include <llvm-c/Target.h>
 #include <llvm-c/TargetMachine.h>
 #include <llvm-c/Core.h>
-#include <target_info/target_info.h>
 #include "compiler_internal.h"
 
 static unsigned arch_pointer_bit_width(OsType os, ArchType arch);
@@ -426,6 +425,8 @@ static inline void target_setup_x64_abi(BuildTarget *target)
 	platform_target.abi = ABI_X64;
 	platform_target.x64.avx_level = AVX;
 	platform_target.x64.is_win64 = platform_target.os == OS_TYPE_WIN32;
+	if (target->feature.avx512) platform_target.x64.avx_level = AVX_512;
+	if (target->feature.avx) platform_target.x64.avx_level = AVX;
 	if (target->feature.no_avx) platform_target.x64.avx_level = AVX_NONE;
 	if (target->feature.no_mmx) platform_target.x64.no_mmx = true;
 	if (target->feature.no_sse) platform_target.x64.no_sse = true;
diff --git a/src/compiler/types.c b/src/compiler/types.c
index 0b09f8fc3..5fe42b9e2 100644
--- a/src/compiler/types.c
+++ b/src/compiler/types.c
@@ -1035,7 +1035,6 @@ static int compare_function(FunctionSignature *sig, FunctionPrototype *proto)
 	return 0;
 }
 
-void c_abi_func_create(FunctionPrototype *proto);
 
 static inline Type *func_create_new_func_proto(FunctionSignature *sig, CallABI abi, uint32_t hash, FuncTypeEntry *entry)
 {
diff --git a/src/target_info/target_info.c b/src/target_info/target_info.c
deleted file mode 100644
index a58c2d7fe..000000000
--- a/src/target_info/target_info.c
+++ /dev/null
@@ -1,73 +0,0 @@
-// Copyright (c) 2020 Christoffer Lerno. All rights reserved.
-// Use of this source code is governed by a LGPLv3.0
-// a copy of which can be found in the LICENSE file.
-
-#include "target_info_internal.h"
-
-typedef enum
-{
-	AVXABI_LEVEL_NONE,
-	AVXABI_AVX,
-	AVXABI_512
-} X86AVXABILevel;
-
-static unsigned x86avxabi_vector_size(X86AVXABILevel level)
-{
-	switch (level)
-	{
-		case AVXABI_512:
-			return 512;
-		case AVXABI_AVX:
-			return 256;
-		case AVXABI_LEVEL_NONE:
-			return 128;
-	}
-	UNREACHABLE
-}
-
-TargetInfo target_info_new()
-{
-	// From the glibc documentation, on GNU systems, malloc guarantees 16-byte
-	// alignment on 64-bit systems and 8-byte alignment on 32-bit systems. See
-	// https://www.gnu.org/software/libc/manual/html_node/Malloc-Examples.html.
-	// This alignment guarantee also applies to Windows and Android.
-	/*
-	if (T.isGNUEnvironment() || T.isWindowsMSVCEnvironment() || T.isAndroid())
-		NewAlign = Triple.isArch64Bit() ? 128 : Triple.isArch32Bit() ? 64 : 0;
-	else
-		NewAlign = 0; // Infer from basic type alignment.
-	*/
-	TargetInfo target_info = {
-		.little_endian = true,
-		.asm_supported = false,
-		.float_128 = false,
-		.float_16 = false,
-		.align_pointer = 8,
-		.align_char = 8,
-		.align_c_int = 32,
-		.align_c_long = 32,
-		.align_c_long_long = 64,
-		.align_c_long_double = 64,
-		.align_f128 = 128,
-		.align_large_array = 0,
-		.align_global_min = 0,
-		.align_new = 0,
-		.align_max_vector = 0,
-		.align_simd_default = 0,
-		.width_pointer = 32,
-		.width_c_int = 32,
-		.width_c_long = 32,
-		.width_c_long_long = 64,
-		.width_c_long_double = 64,
-		.width_large_array_min = 0,
-		.width_c_wchar = 32,
-		.width_c_wint = 32,
-		.reg_param_max = 0,
-		.sse_reg_param_max = 0,
-		.builtin_ms_valist = false,
-		.aarch64sve_types = false,
-		.platform_name = "unknown"
-	};
-	return target_info;
-}
-
diff --git a/src/target_info/target_info.h b/src/target_info/target_info.h
deleted file mode 100644
index 4bad859a1..000000000
--- a/src/target_info/target_info.h
+++ /dev/null
@@ -1,87 +0,0 @@
-#pragma once
-
-// Copyright (c) 2020 Christoffer Lerno. All rights reserved.
-// Use of this source code is governed by a LGPLv3.0
-// a copy of which can be found in the LICENSE file.
-
-#include "utils/common.h"
-
-
-
-
-typedef enum
-{
-	SUB_ARCH_NONE,
-	SUB_ARCH_ARM_V8_5A,
-	SUB_ARCH_ARM_V8_4A,
-	SUB_ARCH_ARM_V8_3A,
-	SUB_ARCH_ARM_V8_2A,
-	SUB_ARCH_ARM_V8_1A,
-	SUB_ARCH_ARM_V8,
-	SUB_ARCH_ARM_V8R,
-	SUB_ARCH_ARM_V8M_BASELINE,
-	SUB_ARCH_ARM_V8M_MAINLINE,
-	SUB_ARCH_ARM_V8_1M_MAINLINE,
-	SUB_ARCH_ARM_V7,
-	SUB_ARCH_ARM_V7EM,
-	SUB_ARCH_ARM_V7M,
-	SUB_ARCH_ARM_V7S,
-	SUB_ARCH_ARM_V7K,
-	SUB_ARCH_ARM_V7VE,
-	SUB_ARCH_ARM_V6,
-	SUB_ARCH_ARM_V6M,
-	SUB_ARCH_ARM_V6K,
-	SUB_ARCH_ARM_V6T2,
-	SUB_ARCH_ARM_V5,
-	SUB_ARCH_ARM_V5TE,
-	SUB_ARCH_ARM_V4,
-	SUB_ARCH_KALIMBA_V3,
-	SUB_ARCH_KALIMBA_V4,
-	SUB_ARCH_KALIMBA_V5,
-	SUB_ARCH_MIPS_V6,
-} SubArchType;
-
-
-
-
-
-typedef struct
-{
-	bool little_endian;
-	bool tls_supported;
-	bool asm_supported;
-	bool float_128;
-	bool float_16;
-	unsigned align_pointer;
-	unsigned align_char;
-	unsigned align_short;
-	unsigned align_int;
-	unsigned align_long;
-	unsigned align_half;
-	unsigned align_float;
-	unsigned align_double;
-	unsigned align_f128;
-	unsigned align_c_long_double;
-	unsigned align_c_int;
-	unsigned align_c_long;
-	unsigned align_c_long_long;
-	unsigned align_simd_default;
-	unsigned align_max_vector;
-	unsigned align_global_min;
-	unsigned align_new;
-	unsigned align_large_array;
-	unsigned width_size;
-	unsigned width_pointer;
-	unsigned width_c_int;
-	unsigned width_c_long;
-	unsigned width_c_long_long;
-	unsigned width_c_long_double;
-	unsigned width_c_wchar;
-	unsigned width_c_wint;
-	unsigned width_large_array_min;
-	unsigned reg_param_max;
-	unsigned sse_reg_param_max;
-	unsigned builtin_ms_valist;
-	unsigned aarch64sve_types;
-	char *platform_name;
-} TargetInfo;
diff --git a/src/target_info/target_info_internal.h b/src/target_info/target_info_internal.h
deleted file mode 100644
index 17457796e..000000000
--- a/src/target_info/target_info_internal.h
+++ /dev/null
@@ -1,7 +0,0 @@
-#pragma once
-
-// Copyright (c) 2020 Christoffer Lerno. All rights reserved.
-// Use of this source code is governed by a LGPLv3.0
-// a copy of which can be found in the LICENSE file.
-
-#include "target_info.h"
diff --git a/test/src/tester.py b/test/src/tester.py
index 50ccbf34c..195efc290 100644
--- a/test/src/tester.py
+++ b/test/src/tester.py
@@ -58,6 +58,7 @@ class Issues:
         self.files = []
         self.errors = {}
         self.warnings = {}
+        self.opts = []
 
     def exit_error(self, message):
         print('Error in file ' + self.sourcefile.filepath + ': ' + message)
@@ -109,7 +110,10 @@ class Issues:
             target = " --target " + self.arch
         if (self.debuginfo):
             debug = "-g "
-        code = subprocess.run(self.conf.compiler + target + ' -O0 ' + debug + args, universal_newlines=True, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        opts = ""
+        for opt in self.opts:
+            opts += ' -' + opt
+        code = subprocess.run(self.conf.compiler + target + ' -O0 ' + opts + ' ' + debug + args, universal_newlines=True, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
         os.chdir(self.conf.cwd)
         if code.returncode != 0 and code.returncode != 1:
             self.set_failed()
@@ -141,6 +145,9 @@ class Issues:
         if (line.startswith("debuginfo:")):
             self.debuginfo = line[10:].strip() == "yes"
             return
+        if (line.startswith("opt:")):
+            self.opts.append(line[4:].strip())
+            return
         if (line.startswith("target:")):
             self.arch = line[7:].strip()
             return
diff --git a/test/test_suite/abi/darwin64_avx.c3t b/test/test_suite/abi/darwin64_avx.c3t
new file mode 100644
index 000000000..5fa641ee5
--- /dev/null
+++ b/test/test_suite/abi/darwin64_avx.c3t
@@ -0,0 +1,84 @@
+// #target: x64-darwin
+// #opt: mavx
+module test;
+
+define Mm256 = float[<8>];
+struct St256 {
+  Mm256 m;
+}
+
+St256 x38;
+Mm256 x37;
+
+extern fn void f38(St256 x);
+extern fn void f37(Mm256 x);
+fn void f39() { f38(x38); f37(x37); }
+
+// The two next tests make sure that the struct below is passed
+// in the same way regardless of avx being used
+
+// CHECK: declare void @func40(%struct.t128* byval(%struct.t128) align 16)
+
+define Mm128 = float[<4>];
+struct Two128 {
+  Mm128 m;
+  Mm128 n;
+}
+
+extern fn void func40(Two128 s);
+fn void func41(Two128 s) {
+  func40(s);
+}
+
+struct Atwo128 {
+  Mm128[2] array;
+}
+
+struct Sa {
+  Atwo128 x;
+}
+
+extern fn void func42(Sa s);
+fn void func43(Sa s) {
+  func42(s);
+}
+
+
+define Vec46 = float[<2>];
+extern fn void f46(Vec46,Vec46,Vec46,Vec46,Vec46,Vec46,Vec46,Vec46,Vec46,Vec46);
+fn void test46() { Vec46 x = {1,2}; f46(x,x,x,x,x,x,x,x,x,x); }
+
+struct Vec47 { uint a; }
+extern fn void f47(int,int,int,int,int,int,Vec47);
+fn void test47(int a, Vec47 b) { f47(a, a, a, a, a, a, b); }
+
+fn void test49_helper(double, ...);
+fn void test49(double d, double e) { test49_helper(d, e); }
+
+extern fn void test52_helper(int, ...);
+Mm256 x52;
+fn void test52() {
+  test52_helper(0, x52, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0);
+}
+
+/* #expect: test.ll
+
+declare void @f38(<8 x float>)
+declare void @f37(<8 x float>)
+
+declare void @func40(%Two128* byval(%Two128) align 16)
+define void @test.func41(%Two128* byval(%Two128) align 16 %0)
+
+declare void @func42(%Sa* byval(%Sa) align 16)
+define void @test.func43(%Sa* byval(%Sa) align 16 %0)
+
+declare void @f46(double, double, double, double, double, double, double, double, <2 x float>* byval(<2 x float>) align 8, <2 x float>* byval(<2 x float>) align 8)
+declare void @f47(i32, i32, i32, i32, i32, i32, i32)
+
+declare void @test.test49_helper(double, ...)
+define void @test.test49(double %0, double %1)
+entry:
+  call void (double, ...) @test.test49_helper(double %0, double %1)
+  ret void
+
+call void (i32, ...) @test52_helper(i32 0, <8 x float>* byval(<8 x float>) align 32 %indirectarg, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00)
diff --git a/test/test_suite/abi/darwin64_sse.c3t b/test/test_suite/abi/darwin64_sse.c3t
new file mode 100644
index 000000000..a5f72c419
--- /dev/null
+++ b/test/test_suite/abi/darwin64_sse.c3t
@@ -0,0 +1,55 @@
+// #target: x64-darwin
+// #opt: mno-avx
+module test;
+
+define Mm256 = float[<8>];
+struct St256 {
+  Mm256 m;
+}
+
+St256 x38;
+Mm256 x37;
+
+extern fn void f38(St256 x);
+extern fn void f37(Mm256 x);
+fn void f39() { f38(x38); f37(x37); }
+
+// The two next tests make sure that the struct below is passed
+// in the same way regardless of avx being used
+
+// CHECK: declare void @func40(%struct.t128* byval(%struct.t128) align 16)
+
+define Mm128 = float[<4>];
+struct Two128 {
+  Mm128 m;
+  Mm128 n;
+}
+
+extern fn void func40(Two128 s);
+fn void func41(Two128 s) {
+  func40(s);
+}
+
+struct Atwo128 {
+  Mm128[2] array;
+}
+
+struct Sa {
+  Atwo128 x;
+}
+
+extern fn void func42(Sa s);
+fn void func43(Sa s) {
+  func42(s);
+}
+
+/* #expect: test.ll
+
+declare void @f38(%St256* byval(%St256) align 32)
+declare void @f37(<8 x float>* byval(<8 x float>) align 32)
+
+declare void @func40(%Two128* byval(%Two128) align 16)
+define void @test.func41(%Two128* byval(%Two128) align 16 %0)
+
+declare void @func42(%Sa* byval(%Sa) align 16)
+define void @test.func43(%Sa* byval(%Sa) align 16 %0)
diff --git a/test/test_suite/abi/darwinx64_2.c3t b/test/test_suite/abi/darwinx64_2.c3t
index be5684fc1..239d81250 100644
--- a/test/test_suite/abi/darwinx64_2.c3t
+++ b/test/test_suite/abi/darwinx64_2.c3t
@@ -64,6 +64,86 @@ fn float[<4>] f25(float[<4>] x) {
   return x+x;
 }
 
+struct Foo26 {
+  int *x;
+  float *y;
+}
+
+fn Foo26 f26(Foo26 *p) {
+  return *p;
+}
+
+
+struct V4f32wrapper {
+  float[<4>] v;
+}
+
+fn V4f32wrapper f27(V4f32wrapper x) {
+  return x;
+}
+
+// PR22563 - We should unwrap simple structs and arrays to pass
+// and return them in the appropriate vector registers if possible.
+
+define V8f32 = float[<8>];
+struct V8f32wrapper {
+  V8f32 v;
+}
+
+fn V8f32wrapper f27a(V8f32wrapper x) {
+  return x;
+}
+
+struct V8f32wrapper_wrapper {
+  V8f32[1] v;
+}
+
+fn V8f32wrapper_wrapper f27b(V8f32wrapper_wrapper x) {
+  return x;
+}
+
+struct F28c {
+  double x;
+  int y;
+}
+fn void f28(F28c c) {
+}
+
+struct Inner
+{
+    double x;
+    int y;
+}
+struct F29a
+{
+  Inner[1] c;
+}
+
+fn void f29a(F29a a) {
+}
+
+struct St0 {
+    char[8] f0; char f2; char f3; char f4; }
+fn void f30(St0 p_4) {
+}
+
+struct F31foo { float a, b, c; }
+fn float f31(F31foo x) {
+  return x.c;
+}
+
+define V1i64 = ulong[<1>];
+
+fn V1i64 f34(V1i64 arg) { return arg; }
+
+
+define V1i64_2 = uint[<2>];
+fn V1i64_2 f35(V1i64_2 arg) { return arg+arg; }
+
+define V2i32 = float[<2>];
+fn V2i32 f36(V2i32 arg) { return arg; }
+
+
 /* #expect: test.ll
 
 define i32 @test.f12_0()
@@ -91,3 +171,15 @@ entry:
   %fadd = fadd <4 x float> %0, %0
   ret <4 x float> %fadd
 }
+
+define { i32*, float* } @test.f26(%Foo26* %0)
+define <4 x float> @test.f27(<4 x float> %0)
+define <8 x float> @test.f27a(<8 x float> %0)
+define <8 x float> @test.f27b(<8 x float> %0)
+define void @test.f28(double %0, i32 %1)
+define void @test.f29a(double %0, i32 %1)
+define void @test.f30(i64 %0, i24 %1)
+define float @test.f31(<2 x float> %0, float %1)
+define double @test.f34(double %0)
+define double @test.f35(double %0)
+define double @test.f36(double %0)