Index: src/runtime/lookup-asm/lookup-asm-x86_64-elf.S
==================================================================
--- src/runtime/lookup-asm/lookup-asm-x86_64-elf.S
+++ src/runtime/lookup-asm/lookup-asm-x86_64-elf.S
@@ -15,71 +15,69 @@
 
 #include "config.h"
 
 #include "platform.h"
 
-.intel_syntax noprefix
-
 .globl objc_msg_lookup
 .globl objc_msg_lookup_stret
 .globl objc_msg_lookup_super
 .globl objc_msg_lookup_super_stret
 
 .section .text
 .macro generate_lookup name not_found
 \name:
-	test	rdi, rdi
-	jz	short ret_nil
-
-	bt	edi, 0
-	jc	short .Ltagged_pointer_\name
-
-	mov	r8, [rdi]
-	mov	r8, [r8+64]
+	testq	%rdi, %rdi
+	jz	ret_nil
+
+	btl	$0, %edi
+	jc	.Ltagged_pointer_\name
+
+	movq	(%rdi), %r8
+	movq	64(%r8), %r8
 
 .Lmain_\name:
-	mov	rax, [rsi]
-	movzx	ecx, ah
-	movzx	edx, al
+	movq	(%rsi), %rax
+	movzbl	%ah, %ecx
+	movzbl	%al, %edx
 #ifdef OF_SELUID24
-	shr	eax, 16
+	shrl	$16, %eax
 
-	mov	r8,  [r8+rax*8]
+	movq	(%r8,%rax,8), %r8
 #endif
-	mov	r8,  [r8+rcx*8]
-	mov	rax, [r8+rdx*8]
+	movq	(%r8,%rcx,8), %r8
+	movq	(%r8,%rdx,8), %rax
 
-	test	rax, rax
-	jz	short \not_found@PLT
+	testq	%rax, %rax
+	jz	\not_found@PLT
 
 	ret
 
 .Ltagged_pointer_\name:
-	mov	rax, [rip+objc_tagged_pointer_secret@GOTPCREL]
-	xor	rdi, [rax]
-	and	dil, 0xE
-	movzx	r8, dil
-
-	mov	rax, [rip+objc_tagged_pointer_classes@GOTPCREL]
-	mov	r8, [rax+r8*4]
-	mov	r8, [r8+64]
-
-	jmp	short .Lmain_\name
+	movq	objc_tagged_pointer_secret@GOTPCREL(%rip), %rax
+	xorq	(%rax), %rdi
+	andb	$0xE, %dil
+	movzbl	%dil, %r8d
+
+	movq	objc_tagged_pointer_classes@GOTPCREL(%rip), %rax
+	movq	(%rax,%r8,4), %r8
+	movq	64(%r8), %r8
+
+	jmp	.Lmain_\name
 .type \name, %function
 .size \name, .-\name
 .endm
 
 .macro generate_lookup_super name lookup
 \name:
-	mov	r8, rdi
-	mov	rdi, [rdi]
-	test	rdi, rdi
-	jz	short ret_nil
-
-	mov	r8, [r8+8]
-	mov	r8, [r8+64]
-	jmp	short .Lmain_\lookup
+	movq	%rdi, %r8
+	movq	(%rdi), %rdi
+	testq	%rdi, %rdi
+	jz	ret_nil
+
+	movq	8(%r8), %r8
+	movq	64(%r8), %r8
+	jmp	.Lmain_\lookup
 .type \name, %function
 .size \name, .-\name
 .endm
 
 generate_lookup objc_msg_lookup objc_method_not_found
@@ -86,15 +84,15 @@
 generate_lookup objc_msg_lookup_stret objc_method_not_found_stret
 generate_lookup_super objc_msg_lookup_super objc_msg_lookup
 generate_lookup_super objc_msg_lookup_super_stret objc_msg_lookup_stret
 
 ret_nil:
-	lea	rax, [rip+nil_method]
+	leaq	nil_method(%rip), %rax
 	ret
 
 nil_method:
-	xor	rax, rax
+	xorq	%rax, %rax
 	ret
 
 #ifdef OF_LINUX
 .section .note.GNU-stack, "", %progbits
 #endif

Index: src/runtime/lookup-asm/lookup-asm-x86_64-macho.S
==================================================================
--- src/runtime/lookup-asm/lookup-asm-x86_64-macho.S
+++ src/runtime/lookup-asm/lookup-asm-x86_64-macho.S
@@ -51,11 +51,11 @@
 
 Ltagged_pointer_$0:
 	movq	_objc_tagged_pointer_secret@GOTPCREL(%rip), %rax
 	xorq	(%rax), %rdi
 	andb	$$0xE, %dil
-	movzbq	%dil, %r8
+	movzbl	%dil, %r8d
 
 	movq	_objc_tagged_pointer_classes@GOTPCREL(%rip), %rax
 	movq	(%rax,%r8,4), %r8
 	movq	64(%r8), %r8
 
@@ -82,7 +82,7 @@
 ret_nil:
 	leaq	nil_method(%rip), %rax
 	ret
 
 nil_method:
-	movq	%rdi, %rax
+	xorq	%rax, %rax
 	ret