diff --git a/library/stdarch/crates/core_arch/src/x86/bt.rs b/library/stdarch/crates/core_arch/src/x86/bt.rs
index 4c588b424ca2..e7728a9cf88e 100644
--- a/library/stdarch/crates/core_arch/src/x86/bt.rs
+++ b/library/stdarch/crates/core_arch/src/x86/bt.rs
@@ -8,12 +8,12 @@ use stdarch_test::assert_instr;
 pub unsafe fn _bittest(p: *const i32, b: i32) -> u8 {
     let r: u8;
     asm!(
-        "bt [{p}], {b:e}",
+        "btl {b:e}, ({p})",
         "setc {r}",
         p = in(reg) p,
         b = in(reg) b,
         r = out(reg_byte) r,
-        options(readonly, nostack, pure)
+        options(readonly, nostack, pure, att_syntax)
     );
     r
 }
@@ -25,12 +25,12 @@ pub unsafe fn _bittest(p: *const i32, b: i32) -> u8 {
 pub unsafe fn _bittestandset(p: *mut i32, b: i32) -> u8 {
     let r: u8;
     asm!(
-        "bts [{p}], {b:e}",
+        "btsl {b:e}, ({p})",
         "setc {r}",
         p = in(reg) p,
         b = in(reg) b,
         r = out(reg_byte) r,
-        options(nostack)
+        options(nostack, att_syntax)
     );
     r
 }
@@ -42,12 +42,12 @@ pub unsafe fn _bittestandset(p: *mut i32, b: i32) -> u8 {
 pub unsafe fn _bittestandreset(p: *mut i32, b: i32) -> u8 {
     let r: u8;
     asm!(
-        "btr [{p}], {b:e}",
+        "btrl {b:e}, ({p})",
         "setc {r}",
         p = in(reg) p,
         b = in(reg) b,
         r = out(reg_byte) r,
-        options(nostack)
+        options(nostack, att_syntax)
     );
     r
 }
@@ -59,12 +59,12 @@ pub unsafe fn _bittestandreset(p: *mut i32, b: i32) -> u8 {
 pub unsafe fn _bittestandcomplement(p: *mut i32, b: i32) -> u8 {
     let r: u8;
     asm!(
-        "btc [{p}], {b:e}",
+        "btcl {b:e}, ({p})",
         "setc {r}",
         p = in(reg) p,
         b = in(reg) b,
         r = out(reg_byte) r,
-        options(nostack)
+        options(nostack, att_syntax)
     );
     r
 }
diff --git a/library/stdarch/crates/core_arch/src/x86/cpuid.rs b/library/stdarch/crates/core_arch/src/x86/cpuid.rs
index 1ae132c4034c..ed383e917d5d 100644
--- a/library/stdarch/crates/core_arch/src/x86/cpuid.rs
+++ b/library/stdarch/crates/core_arch/src/x86/cpuid.rs
@@ -61,27 +61,27 @@ pub unsafe fn __cpuid_count(leaf: u32, sub_leaf: u32) -> CpuidResult {
     #[cfg(target_arch = "x86")]
     {
         asm!(
-            "mov {0}, ebx",
+            "movl %ebx, {0}",
             "cpuid",
-            "xchg {0}, ebx",
+            "xchgl %ebx, {0}",
             lateout(reg) ebx,
             inlateout("eax") leaf => eax,
             inlateout("ecx") sub_leaf => ecx,
             lateout("edx") edx,
-            options(nostack, preserves_flags),
+            options(nostack, preserves_flags, att_syntax),
         );
     }
     #[cfg(target_arch = "x86_64")]
     {
         asm!(
-            "mov {0:r}, rbx",
+            "movq %rbx, {0:r}",
             "cpuid",
-            "xchg {0:r}, rbx",
+            "xchgq %rbx, {0:r}",
             lateout(reg) ebx,
             inlateout("eax") leaf => eax,
             inlateout("ecx") sub_leaf => ecx,
             lateout("edx") edx,
-            options(nostack, preserves_flags),
+            options(nostack, preserves_flags, att_syntax),
         );
     }
     CpuidResult { eax, ebx, ecx, edx }
@@ -130,9 +130,9 @@ pub fn has_cpuid() -> bool {
                 // Read eflags and save a copy of it
                 "pushfd",
                 "pop {result}",
-                "mov {saved_flags}, {result}",
+                "mov {result}, {saved_flags}",
                 // Flip 21st bit of the flags
-                "xor {result}, 0x200000",
+                "xor $0x200000, {result}",
                 // Load the modified flags and read them back.
                 // Bit 21 can only be modified if cpuid is available.
                 "push {result}",
@@ -140,10 +140,10 @@ pub fn has_cpuid() -> bool {
                 "pushfd",
                 "pop {result}",
                 // Use xor to find out whether bit 21 has changed
-                "xor {result}, {saved_flags}",
+                "xor {saved_flags}, {result}",
                 result = out(reg) result,
                 saved_flags = out(reg) _,
-                options(nomem),
+                options(nomem, att_syntax),
             );
             // There is a race between popfd (A) and pushfd (B)
             // where other bits beyond 21st may have been modified due to
diff --git a/library/stdarch/crates/core_arch/src/x86/eflags.rs b/library/stdarch/crates/core_arch/src/x86/eflags.rs
index 80e950e45674..368240378f45 100644
--- a/library/stdarch/crates/core_arch/src/x86/eflags.rs
+++ b/library/stdarch/crates/core_arch/src/x86/eflags.rs
@@ -13,7 +13,7 @@
 #[doc(hidden)]
 pub unsafe fn __readeflags() -> u32 {
     let eflags: u32;
-    asm!("pushfd", "pop {}", out(reg) eflags, options(nomem));
+    asm!("pushfd", "pop {}", out(reg) eflags, options(nomem, att_syntax));
     eflags
 }
 
@@ -30,7 +30,7 @@ pub unsafe fn __readeflags() -> u32 {
 #[doc(hidden)]
 pub unsafe fn __readeflags() -> u64 {
     let eflags: u64;
-    asm!("pushfq", "pop {}", out(reg) eflags, options(nomem));
+    asm!("pushfq", "pop {}", out(reg) eflags, options(nomem, att_syntax));
     eflags
 }
 
@@ -46,7 +46,7 @@ pub unsafe fn __readeflags() -> u64 {
 )]
 #[doc(hidden)]
 pub unsafe fn __writeeflags(eflags: u32) {
-    asm!("push {}", "popfd", in(reg) eflags, options(nomem));
+    asm!("push {}", "popfd", in(reg) eflags, options(nomem, att_syntax));
 }
 
 /// Write EFLAGS.
@@ -61,7 +61,7 @@ pub unsafe fn __writeeflags(eflags: u32) {
 )]
 #[doc(hidden)]
 pub unsafe fn __writeeflags(eflags: u64) {
-    asm!("push {}", "popfq", in(reg) eflags, options(nomem));
+    asm!("push {}", "popfq", in(reg) eflags, options(nomem, att_syntax));
 }
 
 #[cfg(test)]
diff --git a/library/stdarch/crates/core_arch/src/x86_64/bt.rs b/library/stdarch/crates/core_arch/src/x86_64/bt.rs
index 0e4fcd7b2ab8..96788f0e833b 100644
--- a/library/stdarch/crates/core_arch/src/x86_64/bt.rs
+++ b/library/stdarch/crates/core_arch/src/x86_64/bt.rs
@@ -8,12 +8,12 @@ use stdarch_test::assert_instr;
 pub unsafe fn _bittest64(p: *const i64, b: i64) -> u8 {
     let r: u8;
     asm!(
-        "bt [{p}], {b}",
+        "btq {b}, ({p})",
         "setc {r}",
         p = in(reg) p,
         b = in(reg) b,
         r = out(reg_byte) r,
-        options(readonly, nostack, pure)
+        options(readonly, nostack, pure, att_syntax)
     );
     r
 }
@@ -25,12 +25,12 @@ pub unsafe fn _bittest64(p: *const i64, b: i64) -> u8 {
 pub unsafe fn _bittestandset64(p: *mut i64, b: i64) -> u8 {
     let r: u8;
     asm!(
-        "bts [{p}], {b}",
+        "btsq {b}, ({p})",
         "setc {r}",
         p = in(reg) p,
         b = in(reg) b,
         r = out(reg_byte) r,
-        options(nostack)
+        options(nostack, att_syntax)
     );
     r
 }
@@ -42,12 +42,12 @@ pub unsafe fn _bittestandset64(p: *mut i64, b: i64) -> u8 {
 pub unsafe fn _bittestandreset64(p: *mut i64, b: i64) -> u8 {
     let r: u8;
     asm!(
-        "btr [{p}], {b}",
+        "btrq {b}, ({p})",
         "setc {r}",
         p = in(reg) p,
         b = in(reg) b,
         r = out(reg_byte) r,
-        options(nostack)
+        options(nostack, att_syntax)
     );
     r
 }
@@ -59,12 +59,12 @@ pub unsafe fn _bittestandreset64(p: *mut i64, b: i64) -> u8 {
 pub unsafe fn _bittestandcomplement64(p: *mut i64, b: i64) -> u8 {
     let r: u8;
     asm!(
-        "btc [{p}], {b}",
+        "btcq {b}, ({p})",
         "setc {r}",
         p = in(reg) p,
         b = in(reg) b,
         r = out(reg_byte) r,
-        options(nostack)
+        options(nostack, att_syntax)
     );
     r
 }