diff --git a/clang/include/clang/Basic/BuiltinsAArch64.def b/clang/include/clang/Basic/BuiltinsAArch64.def
index eaae6c9ad84686..12c7a371e0fbdb 100644
--- a/clang/include/clang/Basic/BuiltinsAArch64.def
+++ b/clang/include/clang/Basic/BuiltinsAArch64.def
@@ -259,7 +259,6 @@ TARGET_HEADER_BUILTIN(__umulh, "ULLiULLiULLi", "nh", INTRIN_H, ALL_MS_LANGUAGES,
 
 TARGET_HEADER_BUILTIN(__break, "vi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
 
-
 TARGET_HEADER_BUILTIN(__writex18byte,  "vUNiUc", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
 TARGET_HEADER_BUILTIN(__writex18word,  "vUNiUs", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
 TARGET_HEADER_BUILTIN(__writex18dword, "vUNiUNi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
@@ -270,6 +269,20 @@ TARGET_HEADER_BUILTIN(__readx18word,  "UsUNi", "nh", INTRIN_H, ALL_MS_LANGUAGES,
 TARGET_HEADER_BUILTIN(__readx18dword, "UNiUNi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
 TARGET_HEADER_BUILTIN(__readx18qword, "ULLiUNi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
 
+TARGET_HEADER_BUILTIN(_CopyDoubleFromInt64, "dSLLi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+TARGET_HEADER_BUILTIN(_CopyFloatFromInt32, "fSi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+TARGET_HEADER_BUILTIN(_CopyInt32FromFloat, "Sif", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+TARGET_HEADER_BUILTIN(_CopyInt64FromDouble, "SLLid", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+
+TARGET_HEADER_BUILTIN(_CountLeadingOnes, "UiUNi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+TARGET_HEADER_BUILTIN(_CountLeadingOnes64, "UiULLi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+TARGET_HEADER_BUILTIN(_CountLeadingSigns, "UiSNi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+TARGET_HEADER_BUILTIN(_CountLeadingSigns64, "UiSLLi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+TARGET_HEADER_BUILTIN(_CountLeadingZeros, "UiUNi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+TARGET_HEADER_BUILTIN(_CountLeadingZeros64, "UiULLi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+TARGET_HEADER_BUILTIN(_CountOneBits, "UiUNi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+TARGET_HEADER_BUILTIN(_CountOneBits64, "UiULLi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+
 #undef BUILTIN
 #undef LANGBUILTIN
 #undef TARGET_BUILTIN
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index f727a0d5592eff..4a73403cb3b9a7 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -10779,6 +10779,61 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
     return Load;
   }
 
+  if (BuiltinID == AArch64::BI_CopyDoubleFromInt64 ||
+      BuiltinID == AArch64::BI_CopyFloatFromInt32 ||
+      BuiltinID == AArch64::BI_CopyInt32FromFloat ||
+      BuiltinID == AArch64::BI_CopyInt64FromDouble) {
+    Value *Arg = EmitScalarExpr(E->getArg(0));
+    llvm::Type *RetTy = ConvertType(E->getType());
+    return Builder.CreateBitCast(Arg, RetTy);
+  }
+
+  if (BuiltinID == AArch64::BI_CountLeadingOnes ||
+      BuiltinID == AArch64::BI_CountLeadingOnes64 ||
+      BuiltinID == AArch64::BI_CountLeadingZeros ||
+      BuiltinID == AArch64::BI_CountLeadingZeros64) {
+    Value *Arg = EmitScalarExpr(E->getArg(0));
+    llvm::Type *ArgType = Arg->getType();
+
+    if (BuiltinID == AArch64::BI_CountLeadingOnes ||
+        BuiltinID == AArch64::BI_CountLeadingOnes64)
+      Arg = Builder.CreateXor(Arg, Constant::getAllOnesValue(ArgType));
+
+    Function *F = CGM.getIntrinsic(Intrinsic::ctlz, ArgType);
+    Value *Result = Builder.CreateCall(F, {Arg, Builder.getInt1(false)});
+
+    if (BuiltinID == AArch64::BI_CountLeadingOnes64 ||
+        BuiltinID == AArch64::BI_CountLeadingZeros64)
+      Result = Builder.CreateTrunc(Result, Builder.getInt32Ty());
+    return Result;
+  }
+
+  if (BuiltinID == AArch64::BI_CountLeadingSigns ||
+      BuiltinID == AArch64::BI_CountLeadingSigns64) {
+    Value *Arg = EmitScalarExpr(E->getArg(0));
+
+    Function *F = (BuiltinID == AArch64::BI_CountLeadingSigns)
+                      ? CGM.getIntrinsic(Intrinsic::aarch64_cls)
+                      : CGM.getIntrinsic(Intrinsic::aarch64_cls64);
+
+    Value *Result = Builder.CreateCall(F, Arg, "cls");
+    if (BuiltinID == AArch64::BI_CountLeadingSigns64)
+      Result = Builder.CreateTrunc(Result, Builder.getInt32Ty());
+    return Result;
+  }
+
+  if (BuiltinID == AArch64::BI_CountOneBits ||
+      BuiltinID == AArch64::BI_CountOneBits64) {
+    Value *ArgValue = EmitScalarExpr(E->getArg(0));
+    llvm::Type *ArgType = ArgValue->getType();
+    Function *F = CGM.getIntrinsic(Intrinsic::ctpop, ArgType);
+
+    Value *Result = Builder.CreateCall(F, ArgValue);
+    if (BuiltinID == AArch64::BI_CountOneBits64)
+      Result = Builder.CreateTrunc(Result, Builder.getInt32Ty());
+    return Result;
+  }
+
   // Handle MSVC intrinsics before argument evaluation to prevent double
   // evaluation.
   if (std::optional<MSVCIntrin> MsvcIntId =
diff --git a/clang/lib/Headers/intrin.h b/clang/lib/Headers/intrin.h
index de68b07491c6c5..4678c527bfaab5 100644
--- a/clang/lib/Headers/intrin.h
+++ b/clang/lib/Headers/intrin.h
@@ -572,6 +572,20 @@ unsigned char __readx18byte(unsigned long offset);
 unsigned short __readx18word(unsigned long offset);
 unsigned long __readx18dword(unsigned long offset);
 unsigned __int64 __readx18qword(unsigned long offset);
+
+double _CopyDoubleFromInt64(__int64);
+float _CopyFloatFromInt32(__int32);
+__int32 _CopyInt32FromFloat(float);
+__int64 _CopyInt64FromDouble(double);
+
+unsigned int _CountLeadingOnes(unsigned long);
+unsigned int _CountLeadingOnes64(unsigned __int64);
+unsigned int _CountLeadingSigns(long);
+unsigned int _CountLeadingSigns64(__int64);
+unsigned int _CountLeadingZeros(unsigned long);
+unsigned int _CountLeadingZeros64(unsigned _int64);
+unsigned int _CountOneBits(unsigned long);
+unsigned int _CountOneBits64(unsigned __int64);
 #endif
 
 /*----------------------------------------------------------------------------*\
diff --git a/clang/test/CodeGen/arm64-microsoft-intrinsics.c b/clang/test/CodeGen/arm64-microsoft-intrinsics.c
index bd8e4cb27e5268..b15defb0894e92 100644
--- a/clang/test/CodeGen/arm64-microsoft-intrinsics.c
+++ b/clang/test/CodeGen/arm64-microsoft-intrinsics.c
@@ -265,5 +265,143 @@ unsigned __int64 check__readx18qword(unsigned LONG offset) {
 // CHECK-MSCOMPAT: %[[RETVAL:.*]] = load i64, ptr %[[PTR]], align 1
 // CHECK-MSCOMPAT: ret i64 %[[RETVAL]]
 
+double check__CopyDoubleFromInt64(__int64 arg1) {
+  return _CopyDoubleFromInt64(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG:.*]].addr = alloca i64, align 8
+// CHECK-MSCOMPAT: store i64 %[[ARG]], ptr %[[ARG]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load i64, ptr %[[ARG]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR1:.*]] = bitcast i64 %[[VAR0]] to double
+// CHECK-MSCOMPAT: ret double %[[VAR1]]
+// CHECK-LINUX: error: call to undeclared function '_CopyDoubleFromInt64'
+
+float check__CopyFloatFromInt32(__int32 arg1) {
+  return _CopyFloatFromInt32(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG:.*]].addr = alloca i32, align 4
+// CHECK-MSCOMPAT: store i32 %[[ARG]], ptr %[[ARG]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load i32, ptr %[[ARG]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR1:.*]] = bitcast i32 %[[VAR0]] to float
+// CHECK-MSCOMPAT: ret float %[[VAR1]]
+// CHECK-LINUX: error: call to undeclared function '_CopyFloatFromInt32'
+
+__int32 check__CopyInt32FromFloat(float arg1) {
+  return _CopyInt32FromFloat(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG:.*]].addr = alloca float, align 4
+// CHECK-MSCOMPAT: store float %[[ARG]], ptr %[[ARG]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load float, ptr %[[ARG]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR1:.*]] = bitcast float %[[VAR0]] to i32
+// CHECK-MSCOMPAT: ret i32 %[[VAR1]]
+// CHECK-LINUX: error: call to undeclared function '_CopyInt32FromFloat'
+
+__int64 check__CopyInt64FromDouble(double arg1) {
+  return _CopyInt64FromDouble(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG:.*]].addr = alloca double, align 8
+// CHECK-MSCOMPAT: store double %[[ARG]], ptr %[[ARG]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load double, ptr %[[ARG]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR1:.*]] = bitcast double %[[VAR0]] to i64
+// CHECK-MSCOMPAT: ret i64 %[[VAR1]]
+// CHECK-LINUX: error: call to undeclared function '_CopyInt64FromDouble'
+
+unsigned int check__CountLeadingOnes(unsigned LONG arg1) {
+  return _CountLeadingOnes(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG1:.*]].addr = alloca i32, align 4
+// CHECK-MSCOMPAT: store i32 %[[ARG1]], ptr %[[ARG1]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load i32, ptr %[[ARG1]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR1:.*]] = xor i32 %[[VAR0]], -1
+// CHECK-MSCOMPAT: %[[VAR2:.*]] = call i32 @llvm.ctlz.i32(i32 %1, i1 false)
+// CHECK-MSCOMPAT: ret i32 %[[VAR2]]
+// CHECK-LINUX: error: call to undeclared function '_CountLeadingOnes'
+
+unsigned int check__CountLeadingOnes64(unsigned __int64 arg1) {
+  return _CountLeadingOnes64(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG1:.*]].addr = alloca i64, align 8
+// CHECK-MSCOMPAT: store i64 %[[ARG1]], ptr %[[ARG1]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load i64, ptr %[[ARG1]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR1:.*]] = xor i64 %[[VAR0]], -1
+// CHECK-MSCOMPAT: %[[VAR2:.*]] = call i64 @llvm.ctlz.i64(i64 %1, i1 false)
+// CHECK-MSCOMPAT: %[[VAR3:.*]] = trunc i64 %2 to i32
+// CHECK-MSCOMPAT: ret i32 %[[VAR3]]
+// CHECK-LINUX: error: call to undeclared function '_CountLeadingOnes64'
+
+unsigned int check__CountLeadingSigns(__int32 arg1) {
+  return _CountLeadingSigns(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG1:.*]].addr = alloca i32, align 4
+// CHECK-MSCOMPAT: store i32 %[[ARG1]], ptr %[[ARG1]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load i32, ptr %[[ARG1]].addr, align 4
+// CHECK-MSCOMPAT: %[[CLS:.*]] = call i32 @llvm.aarch64.cls(i32 %[[VAR0]])
+// CHECK-MSCOMPAT: ret i32 %[[CLS]]
+// CHECK-LINUX: error: call to undeclared function '_CountLeadingSigns'
+
+unsigned int check__CountLeadingSigns64(__int64 arg1) {
+  return _CountLeadingSigns64(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG1:.*]].addr = alloca i64, align 8
+// CHECK-MSCOMPAT: store i64 %[[ARG1]], ptr %[[ARG1]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load i64, ptr %[[ARG1]].addr, align 8
+// CHECK-MSCOMPAT: %[[CLS:.*]] = call i32 @llvm.aarch64.cls64(i64 %[[VAR0]])
+// CHECK-MSCOMPAT: ret i32 %[[CLS]]
+// CHECK-LINUX: error: call to undeclared function '_CountLeadingSigns64'
+
+unsigned int check__CountLeadingZeros(__int32 arg1) {
+  return _CountLeadingZeros(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG1:.*]].addr = alloca i32, align 4
+// CHECK-MSCOMPAT: store i32 %[[ARG1]], ptr %[[ARG1]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load i32, ptr %[[ARG1]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR1:.*]] = call i32 @llvm.ctlz.i32(i32 %[[VAR0]], i1 false)
+// CHECK-MSCOMPAT: ret i32 %[[VAR1]]
+// CHECK-LINUX: error: call to undeclared function '_CountLeadingZeros'
+
+unsigned int check__CountLeadingZeros64(__int64 arg1) {
+  return _CountLeadingZeros64(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG1:.*]].addr = alloca i64, align 8
+// CHECK-MSCOMPAT: store i64 %[[ARG1]], ptr %[[ARG1]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load i64, ptr %[[ARG1]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR1:.*]] = call i64 @llvm.ctlz.i64(i64 %[[VAR0]], i1 false)
+// CHECK-MSCOMPAT: %[[VAR2:.*]] = trunc i64 %[[VAR1]] to i32
+// CHECK-MSCOMPAT: ret i32 %[[VAR2]]
+// CHECK-LINUX: error: call to undeclared function '_CountLeadingZeros64'
+
+unsigned int check_CountOneBits(unsigned LONG arg1) {
+  return _CountOneBits(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG1:.*]].addr = alloca i32, align 4
+// CHECK-MSCOMPAT: store i32 %[[ARG1]], ptr %[[ARG1]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load i32, ptr %[[ARG1]].addr, align 4
+// CHECK-MSCOMPAT: %[[VAR1:.*]] = call i32 @llvm.ctpop.i32(i32 %0)
+// CHECK-MSCOMPAT: ret i32 %[[VAR1]]
+// CHECK-LINUX: error: call to undeclared function '_CountOneBits'
+
+unsigned int check_CountOneBits64(unsigned __int64 arg1) {
+  return _CountOneBits64(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG1:.*]].addr = alloca i64, align 8
+// CHECK-MSCOMPAT: store i64 %[[ARG1]], ptr %[[ARG1]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load i64, ptr %[[ARG1]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR1:.*]] = call i64 @llvm.ctpop.i64(i64 %0)
+// CHECK-MSCOMPAT: %[[VAR2:.*]] = trunc i64 %1 to i32
+// CHECK-MSCOMPAT: ret i32 %[[VAR2]]
+// CHECK-LINUX: error: call to undeclared function '_CountOneBits64'
+
+
 // CHECK-MSCOMPAT: ![[MD2]] = !{!"x18"}
 // CHECK-MSCOMPAT: ![[MD3]] = !{!"sp"}