Index: clang/test/CodeGen/CSKY/csky-builtins.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/CSKY/csky-builtins.c
@@ -0,0 +1,67 @@
+// RUN: %clang_cc1 -triple csky -emit-llvm -o - %s | FileCheck %s
+
+unsigned char bitrev8(unsigned char data) {
+  // CHECK: define{{.*}} i8 @bitrev8
+  // CHECK: i8 @llvm.bitreverse.i8(i8
+  return __builtin_bitreverse8(data);
+}
+
+unsigned short bitrev16(unsigned short data) {
+  // CHECK: define{{.*}} i16 @bitrev16
+  // CHECK: i16 @llvm.bitreverse.i16(i16
+  return __builtin_bitreverse16(data);
+}
+
+unsigned long bitrev32(unsigned long data) {
+  // CHECK: define{{.*}} i32 @bitrev32
+  // CHECK: i32 @llvm.bitreverse.i32(i32
+  return __builtin_bitreverse32(data);
+}
+
+unsigned long long bitrev64(unsigned long long data) {
+  // CHECK: define{{.*}} i64 @bitrev64
+  // CHECK: i64 @llvm.bitreverse.i64(i64
+  return __builtin_bitreverse64(data);
+}
+
+unsigned char rotleft8(unsigned char x, unsigned char y) {
+  // CHECK: define{{.*}} i8 @rotleft8
+  // CHECK: i8 @llvm.fshl.i8(i8
+  return __builtin_rotateleft8(x, y);
+}
+
+unsigned short rotleft16(unsigned short x, unsigned short y) {
+  // CHECK: define{{.*}} i16 @rotleft16
+  // CHECK: i16 @llvm.fshl.i16(i16
+  return __builtin_rotateleft16(x, y);
+}
+
+unsigned long rotleft32(unsigned long x, unsigned long y) {
+  // CHECK: define{{.*}} i32 @rotleft32
+  // CHECK: i32 @llvm.fshl.i32(i32
+  return __builtin_rotateleft32(x, y);
+}
+
+unsigned long long rotleft64(unsigned long long x, unsigned long long y) {
+  // CHECK: define{{.*}} i64 @rotleft64
+  // CHECK: i64 @llvm.fshl.i64(i64
+  return __builtin_rotateleft64(x, y);
+}
+
+unsigned short byteswap16(unsigned short x) {
+  // CHECK: define{{.*}} i16 @byteswap16
+  // CHECK: i16 @llvm.bswap.i16(i16
+  return __builtin_bswap16(x);
+}
+
+unsigned long byteswap32(unsigned long x) {
+  // CHECK: define{{.*}} i32 @byteswap32
+  // CHECK: i32 @llvm.bswap.i32(i32
+  return __builtin_bswap32(x);
+}
+
+unsigned long long byteswap64(unsigned long long x) {
+  // CHECK: define{{.*}} i64 @byteswap64
+  // CHECK: i64 @llvm.bswap.i64(i64
+  return __builtin_bswap64(x);
+}
Index: llvm/lib/Target/CSKY/CSKYISelLowering.cpp
===================================================================
--- llvm/lib/Target/CSKY/CSKYISelLowering.cpp
+++ llvm/lib/Target/CSKY/CSKYISelLowering.cpp
@@ -59,7 +59,6 @@
   setOperationAction(ISD::UREM, MVT::i32, Expand);
   setOperationAction(ISD::UDIVREM, MVT::i32, Expand);
   setOperationAction(ISD::SDIVREM, MVT::i32, Expand);
-  setOperationAction(ISD::CTTZ, MVT::i32, Expand);
   setOperationAction(ISD::CTPOP, MVT::i32, Expand);
   setOperationAction(ISD::ROTR, MVT::i32, Expand);
   setOperationAction(ISD::SHL_PARTS, MVT::i32, Expand);
@@ -103,6 +102,7 @@
   if (!Subtarget.has2E3()) {
     setOperationAction(ISD::ABS, MVT::i32, Expand);
     setOperationAction(ISD::BITREVERSE, MVT::i32, Expand);
+    setOperationAction(ISD::CTTZ, MVT::i32, Expand);
     setOperationAction(ISD::SDIV, MVT::i32, Expand);
     setOperationAction(ISD::UDIV, MVT::i32, Expand);
   }
Index: llvm/lib/Target/CSKY/CSKYInstrInfo.td
===================================================================
--- llvm/lib/Target/CSKY/CSKYInstrInfo.td
+++ llvm/lib/Target/CSKY/CSKYInstrInfo.td
@@ -1429,6 +1429,7 @@
   let Predicates = [iHas2E3] in {
     def : Pat<(bitreverse GPR:$rx), (BREV32 GPR:$rx)>;
     def : Pat<(bswap GPR:$rx), (REVB32 GPR:$rx)>;
+    def : Pat<(i32 (cttz GPR:$rx)), (FF1 (BREV32 GPR:$rx))>;
   }
   def : Pat<(i32 (ctlz GPR:$rx)), (FF1 GPR:$rx)>;
 }
Index: llvm/test/CodeGen/CSKY/intrinsic.ll
===================================================================
--- llvm/test/CodeGen/CSKY/intrinsic.ll
+++ llvm/test/CodeGen/CSKY/intrinsic.ll
@@ -11,6 +11,17 @@
   ret i32 %nlz
 }
 
+define i32 @cttz(i32 %x) {
+; CHECK-LABEL: cttz:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    brev32 a0, a0
+; CHECK-NEXT:    ff1.32 a0, a0
+; CHECK-NEXT:    rts16
+entry:
+  %ntz = call i32 @llvm.cttz.i32(i32 %x, i1 1)
+  ret i32 %ntz
+}
+
 define i32 @bswap(i32 %x) {
 ; CHECK-LABEL: bswap:
 ; CHECK:       # %bb.0: # %entry
@@ -21,6 +32,17 @@
   ret i32 %revb32
 }
 
+define i16 @bswap16(i16 %x) {
+; CHECK-LABEL: bswap16:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    revb16 a0, a0
+; CHECK-NEXT:    lsri16 a0, a0, 16
+; CHECK-NEXT:    rts16
+entry:
+  %revb16 = call i16 @llvm.bswap.i16(i16 %x)
+  ret i16 %revb16
+}
+
 define i32 @bitreverse(i32 %x) {
 ; CHECK-LABEL: bitreverse:
 ; CHECK:       # %bb.0: # %entry
@@ -32,5 +54,7 @@
 }
 
 declare i32 @llvm.bswap.i32(i32)
+declare i16 @llvm.bswap.i16(i16)
 declare i32 @llvm.ctlz.i32 (i32, i1)
+declare i32 @llvm.cttz.i32 (i32, i1)
 declare i32 @llvm.bitreverse.i32(i32)