diff --git a/clang/lib/Headers/hlsl/hlsl_intrinsics.h b/clang/lib/Headers/hlsl/hlsl_intrinsics.h
--- a/clang/lib/Headers/hlsl/hlsl_intrinsics.h
+++ b/clang/lib/Headers/hlsl/hlsl_intrinsics.h
@@ -476,5 +476,61 @@
 __attribute__((clang_builtin_alias(__builtin_elementwise_min)))
 double4 min(double4, double4);
 
+// reversebits builtins
+#ifdef __HLSL_ENABLE_16_BIT
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int16_t reversebits(int16_t);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int16_t2 reversebits(int16_t2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int16_t3 reversebits(int16_t3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int16_t4 reversebits(int16_t4);
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint16_t reversebits(uint16_t);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint16_t2 reversebits(uint16_t2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint16_t3 reversebits(uint16_t3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint16_t4 reversebits(uint16_t4);
+#endif
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse))) int
+reversebits(int);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int2 reversebits(int2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int3 reversebits(int3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int4 reversebits(int4);
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint reversebits(uint);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint2 reversebits(uint2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint3 reversebits(uint3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint4 reversebits(uint4);
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int64_t reversebits(int64_t);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int64_t2 reversebits(int64_t2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int64_t3 reversebits(int64_t3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+int64_t4 reversebits(int64_t4);
+
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint64_t reversebits(uint64_t);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint64_t2 reversebits(uint64_t2);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint64_t3 reversebits(uint64_t3);
+__attribute__((clang_builtin_alias(__builtin_elementwise_bitreverse)))
+uint64_t4 reversebits(uint64_t4);
 } // namespace hlsl
 #endif //_HLSL_HLSL_INTRINSICS_H_
diff --git a/clang/test/CodeGenHLSL/builtins/bitreverse.hlsl b/clang/test/CodeGenHLSL/builtins/bitreverse.hlsl
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGenHLSL/builtins/bitreverse.hlsl
@@ -0,0 +1,155 @@
+// RUN: %clang_cc1 -std=hlsl2021 -finclude-default-header -x hlsl -triple \
+// RUN:   dxil-pc-shadermodel6.3-library %s -D__HLSL_ENABLE_16_BIT \
+// RUN:   -emit-llvm -disable-llvm-passes -O3 -o - | FileCheck %s
+
+#ifdef __HLSL_ENABLE_16_BIT
+// CHECK: define noundef i16 @
+// CHECK: call i16 @llvm.bitreverse.i16(
+int16_t test_bitreverse_short(int16_t p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i16> @
+// CHECK: call <2 x i16> @llvm.bitreverse.v2i16(
+int16_t2 test_bitreverse_short2(int16_t2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i16> @
+// CHECK: call <3 x i16> @llvm.bitreverse.v3i16
+int16_t3 test_bitreverse_short3(int16_t3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i16> @
+// CHECK: call <4 x i16> @llvm.bitreverse.v4i16
+int16_t4 test_bitreverse_short4(int16_t4 p0)
+{
+	return reversebits(p0);
+}
+
+// CHECK: define noundef i16 @
+// CHECK: call i16 @llvm.bitreverse.i16(
+uint16_t test_bitreverse_ushort(uint16_t p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i16> @
+// CHECK: call <2 x i16> @llvm.bitreverse.v2i16
+uint16_t2 test_bitreverse_ushort2(uint16_t2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i16> @
+// CHECK: call <3 x i16> @llvm.bitreverse.v3i16
+uint16_t3 test_bitreverse_ushort3(uint16_t3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i16> @
+// CHECK: call <4 x i16> @llvm.bitreverse.v4i16
+uint16_t4 test_bitreverse_ushort4(uint16_t4 p0)
+{
+	return reversebits(p0);
+}
+#endif
+
+// CHECK: define noundef i32 @
+// CHECK: call i32 @llvm.bitreverse.i32(
+int test_bitreverse_int(int p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i32> @
+// CHECK: call <2 x i32> @llvm.bitreverse.v2i32
+int2 test_bitreverse_int2(int2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i32> @
+// CHECK: call <3 x i32> @llvm.bitreverse.v3i32
+int3 test_bitreverse_int3(int3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i32> @
+// CHECK: call <4 x i32> @llvm.bitreverse.v4i32
+int4 test_bitreverse_int4(int4 p0)
+{
+	return reversebits(p0);
+}
+
+// CHECK: define noundef i32 @
+// CHECK: call i32 @llvm.bitreverse.i32(
+int test_bitreverse_uint(uint p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i32> @
+// CHECK: call <2 x i32> @llvm.bitreverse.v2i32
+uint2 test_bitreverse_uint2(uint2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i32> @
+// CHECK: call <3 x i32> @llvm.bitreverse.v3i32
+uint3 test_bitreverse_uint3(uint3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i32> @
+// CHECK: call <4 x i32> @llvm.bitreverse.v4i32
+uint4 test_bitreverse_uint4(uint4 p0)
+{
+	return reversebits(p0);
+}
+
+// CHECK: define noundef i64 @
+// CHECK: call i64 @llvm.bitreverse.i64(
+int64_t test_bitreverse_long(int64_t p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i64> @
+// CHECK: call <2 x i64> @llvm.bitreverse.v2i64
+int64_t2 test_bitreverse_long2(int64_t2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i64> @
+// CHECK: call <3 x i64> @llvm.bitreverse.v3i64
+int64_t3 test_bitreverse_long3(int64_t3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i64> @
+// CHECK: call <4 x i64> @llvm.bitreverse.v4i64
+int64_t4 test_bitreverse_long4(int64_t4 p0)
+{
+	return reversebits(p0);
+}
+
+// CHECK: define noundef i64 @
+// CHECK: call i64 @llvm.bitreverse.i64(
+uint64_t test_bitreverse_long(uint64_t p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i64> @
+// CHECK: call <2 x i64> @llvm.bitreverse.v2i64
+uint64_t2 test_bitreverse_long2(uint64_t2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i64> @
+// CHECK: call <3 x i64> @llvm.bitreverse.v3i64
+uint64_t3 test_bitreverse_long3(uint64_t3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i64> @
+// CHECK: call <4 x i64> @llvm.bitreverse.v4i64
+uint64_t4 test_bitreverse_long4(uint64_t4 p0)
+{
+	return reversebits(p0);
+}
diff --git a/clang/test/CodeGenHLSL/builtins/reversebits.hlsl b/clang/test/CodeGenHLSL/builtins/reversebits.hlsl
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGenHLSL/builtins/reversebits.hlsl
@@ -0,0 +1,155 @@
+// RUN: %clang_cc1 -std=hlsl2021 -finclude-default-header -x hlsl -triple \
+// RUN:   dxil-pc-shadermodel6.3-library %s -fnative-half-type \
+// RUN:   -D__HLSL_ENABLE_16_BIT -emit-llvm -disable-llvm-passes -O3 -o - | FileCheck %s
+
+#ifdef __HLSL_ENABLE_16_BIT
+// CHECK: define noundef i16 @
+// CHECK: call i16 @llvm.bitreverse.i16(
+int16_t test_bitreverse_short(int16_t p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i16> @
+// CHECK: call <2 x i16> @llvm.bitreverse.v2i16(
+int16_t2 test_bitreverse_short2(int16_t2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i16> @
+// CHECK: call <3 x i16> @llvm.bitreverse.v3i16
+int16_t3 test_bitreverse_short3(int16_t3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i16> @
+// CHECK: call <4 x i16> @llvm.bitreverse.v4i16
+int16_t4 test_bitreverse_short4(int16_t4 p0)
+{
+	return reversebits(p0);
+}
+
+// CHECK: define noundef i16 @
+// CHECK: call i16 @llvm.bitreverse.i16(
+uint16_t test_bitreverse_ushort(uint16_t p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i16> @
+// CHECK: call <2 x i16> @llvm.bitreverse.v2i16
+uint16_t2 test_bitreverse_ushort2(uint16_t2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i16> @
+// CHECK: call <3 x i16> @llvm.bitreverse.v3i16
+uint16_t3 test_bitreverse_ushort3(uint16_t3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i16> @
+// CHECK: call <4 x i16> @llvm.bitreverse.v4i16
+uint16_t4 test_bitreverse_ushort4(uint16_t4 p0)
+{
+	return reversebits(p0);
+}
+#endif
+
+// CHECK: define noundef i32 @
+// CHECK: call i32 @llvm.bitreverse.i32(
+int test_bitreverse_int(int p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i32> @
+// CHECK: call <2 x i32> @llvm.bitreverse.v2i32
+int2 test_bitreverse_int2(int2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i32> @
+// CHECK: call <3 x i32> @llvm.bitreverse.v3i32
+int3 test_bitreverse_int3(int3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i32> @
+// CHECK: call <4 x i32> @llvm.bitreverse.v4i32
+int4 test_bitreverse_int4(int4 p0)
+{
+	return reversebits(p0);
+}
+
+// CHECK: define noundef i32 @
+// CHECK: call i32 @llvm.bitreverse.i32(
+int test_bitreverse_uint(uint p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i32> @
+// CHECK: call <2 x i32> @llvm.bitreverse.v2i32
+uint2 test_bitreverse_uint2(uint2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i32> @
+// CHECK: call <3 x i32> @llvm.bitreverse.v3i32
+uint3 test_bitreverse_uint3(uint3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i32> @
+// CHECK: call <4 x i32> @llvm.bitreverse.v4i32
+uint4 test_bitreverse_uint4(uint4 p0)
+{
+	return reversebits(p0);
+}
+
+// CHECK: define noundef i64 @
+// CHECK: call i64 @llvm.bitreverse.i64(
+int64_t test_bitreverse_long(int64_t p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i64> @
+// CHECK: call <2 x i64> @llvm.bitreverse.v2i64
+int64_t2 test_bitreverse_long2(int64_t2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i64> @
+// CHECK: call <3 x i64> @llvm.bitreverse.v3i64
+int64_t3 test_bitreverse_long3(int64_t3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i64> @
+// CHECK: call <4 x i64> @llvm.bitreverse.v4i64
+int64_t4 test_bitreverse_long4(int64_t4 p0)
+{
+	return reversebits(p0);
+}
+
+// CHECK: define noundef i64 @
+// CHECK: call i64 @llvm.bitreverse.i64(
+uint64_t test_bitreverse_long(uint64_t p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <2 x i64> @
+// CHECK: call <2 x i64> @llvm.bitreverse.v2i64
+uint64_t2 test_bitreverse_long2(uint64_t2 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <3 x i64> @
+// CHECK: call <3 x i64> @llvm.bitreverse.v3i64
+uint64_t3 test_bitreverse_long3(uint64_t3 p0)
+{
+	return reversebits(p0);
+}
+// CHECK: define noundef <4 x i64> @
+// CHECK: call <4 x i64> @llvm.bitreverse.v4i64
+uint64_t4 test_bitreverse_long4(uint64_t4 p0)
+{
+	return reversebits(p0);
+}