diff --git a/clang/include/clang/Basic/BuiltinsWebAssembly.def b/clang/include/clang/Basic/BuiltinsWebAssembly.def
--- a/clang/include/clang/Basic/BuiltinsWebAssembly.def
+++ b/clang/include/clang/Basic/BuiltinsWebAssembly.def
@@ -66,67 +66,67 @@
 TARGET_BUILTIN(__builtin_wasm_trunc_saturate_u_i64_f64, "LLid", "nc", "nontrapping-fptoint")
 
 // SIMD builtins
-TARGET_BUILTIN(__builtin_wasm_swizzle_v8x16, "V16cV16cV16c", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_swizzle_v8x16, "V16ScV16ScV16Sc", "nc", "simd128")
 
-TARGET_BUILTIN(__builtin_wasm_extract_lane_s_i8x16, "iV16cIi", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_extract_lane_u_i8x16, "iV16cIi", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_extract_lane_s_i8x16, "iV16ScIi", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_extract_lane_u_i8x16, "iV16UcIUi", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_extract_lane_s_i16x8, "iV8sIi", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_extract_lane_u_i16x8, "iV8sIi", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_extract_lane_u_i16x8, "iV8UsIUi", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_extract_lane_i32x4, "iV4iIi", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_extract_lane_i64x2, "LLiV2LLiIi", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_extract_lane_f32x4, "fV4fIi", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_extract_lane_f64x2, "dV2dIi", "nc", "simd128")
 
-TARGET_BUILTIN(__builtin_wasm_replace_lane_i8x16, "V16cV16cIii", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_replace_lane_i8x16, "V16ScV16ScIii", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_replace_lane_i16x8, "V8sV8sIii", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_replace_lane_i32x4, "V4iV4iIii", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_replace_lane_i64x2, "V2LLiV2LLiIiLLi", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_replace_lane_f32x4, "V4fV4fIif", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_replace_lane_f64x2, "V2dV2dIid", "nc", "simd128")
 
-TARGET_BUILTIN(__builtin_wasm_add_saturate_s_i8x16, "V16cV16cV16c", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_add_saturate_u_i8x16, "V16cV16cV16c", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_add_saturate_s_i8x16, "V16ScV16ScV16Sc", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_add_saturate_u_i8x16, "V16UcV16UcV16Uc", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_add_saturate_s_i16x8, "V8sV8sV8s", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_add_saturate_u_i16x8, "V8sV8sV8s", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_add_saturate_u_i16x8, "V8UsV8UsV8Us", "nc", "simd128")
 
-TARGET_BUILTIN(__builtin_wasm_sub_saturate_s_i8x16, "V16cV16cV16c", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_sub_saturate_u_i8x16, "V16cV16cV16c", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_sub_saturate_s_i8x16, "V16ScV16ScV16Sc", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_sub_saturate_u_i8x16, "V16UcV16UcV16Uc", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_sub_saturate_s_i16x8, "V8sV8sV8s", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_sub_saturate_u_i16x8, "V8sV8sV8s", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_sub_saturate_u_i16x8, "V8UsV8UsV8Us", "nc", "simd128")
 
-TARGET_BUILTIN(__builtin_wasm_abs_i8x16, "V16cV16c", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_abs_i8x16, "V16ScV16Sc", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_abs_i16x8, "V8sV8s", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_abs_i32x4, "V4iV4i", "nc", "simd128")
 
-TARGET_BUILTIN(__builtin_wasm_min_s_i8x16, "V16cV16cV16c", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_min_u_i8x16, "V16cV16cV16c", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_max_s_i8x16, "V16cV16cV16c", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_max_u_i8x16, "V16cV16cV16c", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_min_s_i8x16, "V16ScV16ScV16Sc", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_min_u_i8x16, "V16UcV16UcV16Uc", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_max_s_i8x16, "V16ScV16ScV16Sc", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_max_u_i8x16, "V16UcV16UcV16Uc", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_min_s_i16x8, "V8sV8sV8s", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_min_u_i16x8, "V8sV8sV8s", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_min_u_i16x8, "V8UsV8UsV8Us", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_max_s_i16x8, "V8sV8sV8s", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_max_u_i16x8, "V8sV8sV8s", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_max_u_i16x8, "V8UsV8UsV8Us", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_min_s_i32x4, "V4iV4iV4i", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_min_u_i32x4, "V4iV4iV4i", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_min_u_i32x4, "V4UiV4UiV4Ui", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_max_s_i32x4, "V4iV4iV4i", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_max_u_i32x4, "V4iV4iV4i", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_max_u_i32x4, "V4UiV4UiV4Ui", "nc", "simd128")
 
-TARGET_BUILTIN(__builtin_wasm_avgr_u_i8x16, "V16cV16cV16c", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_avgr_u_i16x8, "V8sV8sV8s", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_avgr_u_i8x16, "V16UcV16UcV16Uc", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_avgr_u_i16x8, "V8UsV8UsV8Us", "nc", "simd128")
 
 TARGET_BUILTIN(__builtin_wasm_bitselect, "V4iV4iV4iV4i", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_shuffle_v8x16, "V16cV16cV16cIiIiIiIiIiIiIiIiIiIiIiIiIiIiIiIi", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_shuffle_v8x16, "V16ScV16ScV16ScIiIiIiIiIiIiIiIiIiIiIiIiIiIiIiIi", "nc", "simd128")
 
-TARGET_BUILTIN(__builtin_wasm_any_true_i8x16, "iV16c", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_any_true_i8x16, "iV16Sc", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_any_true_i16x8, "iV8s", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_any_true_i32x4, "iV4i", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_any_true_i64x2, "iV2LLi", "nc", "unimplemented-simd128")
-TARGET_BUILTIN(__builtin_wasm_all_true_i8x16, "iV16c", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_all_true_i8x16, "iV16Sc", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_all_true_i16x8, "iV8s", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_all_true_i32x4, "iV4i", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_all_true_i64x2, "iV2LLi", "nc", "unimplemented-simd128")
 
-TARGET_BUILTIN(__builtin_wasm_bitmask_i8x16, "iV16c", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_bitmask_i8x16, "iV16Sc", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_bitmask_i16x8, "iV8s", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_bitmask_i32x4, "iV4i", "nc", "simd128")
 
@@ -164,10 +164,10 @@
 TARGET_BUILTIN(__builtin_wasm_trunc_saturate_s_i32x4_f32x4, "V4iV4f", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_trunc_saturate_u_i32x4_f32x4, "V4iV4f", "nc", "simd128")
 
-TARGET_BUILTIN(__builtin_wasm_narrow_s_i8x16_i16x8, "V16cV8sV8s", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_narrow_u_i8x16_i16x8, "V16cV8sV8s", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_narrow_s_i8x16_i16x8, "V16ScV8sV8s", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_narrow_u_i8x16_i16x8, "V16UcV8UsV8Us", "nc", "simd128")
 TARGET_BUILTIN(__builtin_wasm_narrow_s_i16x8_i32x4, "V8sV4iV4i", "nc", "simd128")
-TARGET_BUILTIN(__builtin_wasm_narrow_u_i16x8_i32x4, "V8sV4iV4i", "nc", "simd128")
+TARGET_BUILTIN(__builtin_wasm_narrow_u_i16x8_i32x4, "V8UsV4UiV4Ui", "nc", "simd128")
 
 #undef BUILTIN
 #undef TARGET_BUILTIN
diff --git a/clang/lib/Headers/wasm_simd128.h b/clang/lib/Headers/wasm_simd128.h
--- a/clang/lib/Headers/wasm_simd128.h
+++ b/clang/lib/Headers/wasm_simd128.h
@@ -18,8 +18,7 @@
 
 // Internal types determined by clang builtin definitions
 typedef int32_t __v128_u __attribute__((__vector_size__(16), __aligned__(1)));
-typedef char __i8x16 __attribute__((__vector_size__(16), __aligned__(16)));
-typedef signed char __s8x16
+typedef signed char __i8x16
     __attribute__((__vector_size__(16), __aligned__(16)));
 typedef unsigned char __u8x16
     __attribute__((__vector_size__(16), __aligned__(16)));
@@ -340,17 +339,17 @@
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_i8x16_eq(v128_t __a,
                                                           v128_t __b) {
-  return (v128_t)((__s8x16)__a == (__s8x16)__b);
+  return (v128_t)((__i8x16)__a == (__i8x16)__b);
 }
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_i8x16_ne(v128_t __a,
                                                           v128_t __b) {
-  return (v128_t)((__s8x16)__a != (__s8x16)__b);
+  return (v128_t)((__i8x16)__a != (__i8x16)__b);
 }
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_i8x16_lt(v128_t __a,
                                                           v128_t __b) {
-  return (v128_t)((__s8x16)__a < (__s8x16)__b);
+  return (v128_t)((__i8x16)__a < (__i8x16)__b);
 }
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_u8x16_lt(v128_t __a,
@@ -360,7 +359,7 @@
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_i8x16_gt(v128_t __a,
                                                           v128_t __b) {
-  return (v128_t)((__s8x16)__a > (__s8x16)__b);
+  return (v128_t)((__i8x16)__a > (__i8x16)__b);
 }
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_u8x16_gt(v128_t __a,
@@ -370,7 +369,7 @@
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_i8x16_le(v128_t __a,
                                                           v128_t __b) {
-  return (v128_t)((__s8x16)__a <= (__s8x16)__b);
+  return (v128_t)((__i8x16)__a <= (__i8x16)__b);
 }
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_u8x16_le(v128_t __a,
@@ -380,7 +379,7 @@
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_i8x16_ge(v128_t __a,
                                                           v128_t __b) {
-  return (v128_t)((__s8x16)__a >= (__s8x16)__b);
+  return (v128_t)((__i8x16)__a >= (__i8x16)__b);
 }
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_u8x16_ge(v128_t __a,
@@ -602,7 +601,7 @@
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_i8x16_shr(v128_t __a,
                                                            int32_t __b) {
-  return (v128_t)((__s8x16)__a >> __b);
+  return (v128_t)((__i8x16)__a >> __b);
 }
 
 static __inline__ v128_t __DEFAULT_FN_ATTRS wasm_u8x16_shr(v128_t __a,