diff --git a/clang/include/clang/CIR/Dialect/IR/CIRTypes.td b/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
index 5b53ab6bac6b..82a12963b425 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIRTypes.td
@@ -150,9 +150,36 @@ def CIR_Double : CIR_FloatType<"Double", "double"> {
   }];
 }
 
+def CIR_FP80 : CIR_FloatType<"FP80", "f80"> {
+  let summary = "CIR type that represents x87 80-bit floating-point format";
+  let description = [{
+    Floating-point type that represents the x87 80-bit floating-point format.
+  }];
+}
+
+def CIR_LongDouble : CIR_FloatType<"LongDouble", "long_double"> {
+  let summary = "CIR extended-precision float type";
+  let description = [{
+    Floating-point type that represents the `long double` type in C/C++.
+
+    The underlying floating-point format of a long double value depends on the
+    implementation. The `underlying` parameter specifies the CIR floating-point
+    type that corresponds to this format. For now, it can only be either
+    `!cir.double` or `!cir.fp80`.
+  }];
+
+  let parameters = (ins "mlir::Type":$underlying);
+
+  let assemblyFormat = [{
+    `<` $underlying `>`
+  }];
+
+  let genVerifyDecl = 1;
+}
+
 // Constraints
 
-def CIR_AnyFloat: AnyTypeOf<[CIR_Single, CIR_Double]>;
+def CIR_AnyFloat: AnyTypeOf<[CIR_Single, CIR_Double, CIR_LongDouble]>;
 def CIR_AnyIntOrFloat: AnyTypeOf<[CIR_AnyFloat, CIR_IntType]>;
 
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/CodeGen/CIRGenBuilder.h b/clang/lib/CIR/CodeGen/CIRGenBuilder.h
index e3d1d825af33..200d8d16b918 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuilder.h
+++ b/clang/lib/CIR/CodeGen/CIRGenBuilder.h
@@ -373,29 +373,18 @@ class CIRGenBuilderTy : public CIRBaseBuilderTy {
   }
   bool isInt(mlir::Type i) { return i.isa<mlir::cir::IntType>(); }
 
-  mlir::Type getLongDouble80BitsTy() const { llvm_unreachable("NYI"); }
-
-  /// Get the proper floating point type for the given semantics.
-  mlir::Type getFloatTyForFormat(const llvm::fltSemantics &format,
-                                 bool useNativeHalf) const {
-    if (&format == &llvm::APFloat::IEEEhalf()) {
-      llvm_unreachable("IEEEhalf float format is NYI");
-    }
-
-    if (&format == &llvm::APFloat::BFloat())
-      llvm_unreachable("BFloat float format is NYI");
-    if (&format == &llvm::APFloat::IEEEsingle())
-      return typeCache.FloatTy;
+  mlir::cir::LongDoubleType
+  getLongDoubleTy(const llvm::fltSemantics &format) const {
     if (&format == &llvm::APFloat::IEEEdouble())
-      return typeCache.DoubleTy;
+      return mlir::cir::LongDoubleType::get(getContext(), typeCache.DoubleTy);
+    if (&format == &llvm::APFloat::x87DoubleExtended())
+      return mlir::cir::LongDoubleType::get(getContext(), typeCache.FP80Ty);
     if (&format == &llvm::APFloat::IEEEquad())
-      llvm_unreachable("IEEEquad float format is NYI");
+      llvm_unreachable("NYI");
     if (&format == &llvm::APFloat::PPCDoubleDouble())
-      llvm_unreachable("PPCDoubleDouble float format is NYI");
-    if (&format == &llvm::APFloat::x87DoubleExtended())
-      return getLongDouble80BitsTy();
+      llvm_unreachable("NYI");
 
-    llvm_unreachable("Unknown float format!");
+    llvm_unreachable("unsupported long double format");
   }
 
   mlir::Type getVirtualFnPtrType(bool isVarArg = false) {
diff --git a/clang/lib/CIR/CodeGen/CIRGenModule.cpp b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
index ecfc3e478131..72ecd13c964a 100644
--- a/clang/lib/CIR/CodeGen/CIRGenModule.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
@@ -135,6 +135,7 @@ CIRGenModule::CIRGenModule(mlir::MLIRContext &context,
   // TODO: BFloatTy
   FloatTy = ::mlir::cir::SingleType::get(builder.getContext());
   DoubleTy = ::mlir::cir::DoubleType::get(builder.getContext());
+  FP80Ty = ::mlir::cir::FP80Type::get(builder.getContext());
   // TODO(cir): perhaps we should abstract long double variations into a custom
   // cir.long_double type. Said type would also hold the semantics for lowering.
 
diff --git a/clang/lib/CIR/CodeGen/CIRGenTypeCache.h b/clang/lib/CIR/CodeGen/CIRGenTypeCache.h
index d5900694c43c..abd7d9d03603 100644
--- a/clang/lib/CIR/CodeGen/CIRGenTypeCache.h
+++ b/clang/lib/CIR/CodeGen/CIRGenTypeCache.h
@@ -39,6 +39,7 @@ struct CIRGenTypeCache {
   // cir.long_double type. Said type would also hold the semantics for lowering.
   mlir::cir::SingleType FloatTy;
   mlir::cir::DoubleType DoubleTy;
+  mlir::cir::FP80Type FP80Ty;
 
   /// int
   mlir::Type UIntTy;
diff --git a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
index eeea32cb8dd3..3c6ea3e6ee1d 100644
--- a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
@@ -479,8 +479,7 @@ mlir::Type CIRGenTypes::ConvertType(QualType T) {
       ResultType = CGM.DoubleTy;
       break;
     case BuiltinType::LongDouble:
-      ResultType = Builder.getFloatTyForFormat(Context.getFloatTypeSemantics(T),
-                                               /*useNativeHalf=*/false);
+      ResultType = Builder.getLongDoubleTy(Context.getFloatTypeSemantics(T));
       break;
     case BuiltinType::Float128:
     case BuiltinType::Ibm128:
diff --git a/clang/lib/CIR/Dialect/IR/CIRTypes.cpp b/clang/lib/CIR/Dialect/IR/CIRTypes.cpp
index 597f611ac65c..619e16e47667 100644
--- a/clang/lib/CIR/Dialect/IR/CIRTypes.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRTypes.cpp
@@ -695,6 +695,67 @@ DoubleType::getPreferredAlignment(const ::mlir::DataLayout &dataLayout,
   return (uint64_t)(getWidth() / 8);
 }
 
+const llvm::fltSemantics &FP80Type::getFloatSemantics() const {
+  return llvm::APFloat::x87DoubleExtended();
+}
+
+llvm::TypeSize
+FP80Type::getTypeSizeInBits(const mlir::DataLayout &dataLayout,
+                            mlir::DataLayoutEntryListRef params) const {
+  return llvm::TypeSize::getFixed(16);
+}
+
+uint64_t FP80Type::getABIAlignment(const mlir::DataLayout &dataLayout,
+                                   mlir::DataLayoutEntryListRef params) const {
+  return 16;
+}
+
+uint64_t
+FP80Type::getPreferredAlignment(const ::mlir::DataLayout &dataLayout,
+                                ::mlir::DataLayoutEntryListRef params) const {
+  return 16;
+}
+
+const llvm::fltSemantics &LongDoubleType::getFloatSemantics() const {
+  return getUnderlying()
+      .cast<mlir::cir::CIRFPTypeInterface>()
+      .getFloatSemantics();
+}
+
+llvm::TypeSize
+LongDoubleType::getTypeSizeInBits(const mlir::DataLayout &dataLayout,
+                                  mlir::DataLayoutEntryListRef params) const {
+  return getUnderlying()
+      .cast<mlir::DataLayoutTypeInterface>()
+      .getTypeSizeInBits(dataLayout, params);
+}
+
+uint64_t
+LongDoubleType::getABIAlignment(const mlir::DataLayout &dataLayout,
+                                mlir::DataLayoutEntryListRef params) const {
+  return getUnderlying().cast<mlir::DataLayoutTypeInterface>().getABIAlignment(
+      dataLayout, params);
+}
+
+uint64_t LongDoubleType::getPreferredAlignment(
+    const ::mlir::DataLayout &dataLayout,
+    mlir::DataLayoutEntryListRef params) const {
+  return getUnderlying()
+      .cast<mlir::DataLayoutTypeInterface>()
+      .getPreferredAlignment(dataLayout, params);
+}
+
+LogicalResult
+LongDoubleType::verify(function_ref<InFlightDiagnostic()> emitError,
+                       mlir::Type underlying) {
+  if (!underlying.isa<DoubleType, FP80Type>()) {
+    emitError() << "invalid underlying type for long double";
+    return failure();
+  }
+
+  return success();
+}
+
 //===----------------------------------------------------------------------===//
 // FuncType Definitions
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
index 4ae47b56d1f7..ad0f065993e0 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
@@ -2956,6 +2956,12 @@ void prepareTypeConverter(mlir::LLVMTypeConverter &converter,
   converter.addConversion([&](mlir::cir::DoubleType type) -> mlir::Type {
     return mlir::FloatType::getF64(type.getContext());
   });
+  converter.addConversion([&](mlir::cir::FP80Type type) -> mlir::Type {
+    return mlir::FloatType::getF80(type.getContext());
+  });
+  converter.addConversion([&](mlir::cir::LongDoubleType type) -> mlir::Type {
+    return converter.convertType(type.getUnderlying());
+  });
   converter.addConversion([&](mlir::cir::FuncType type) -> mlir::Type {
     auto result = converter.convertType(type.getReturnType());
     llvm::SmallVector<mlir::Type> arguments;
diff --git a/clang/test/CIR/CodeGen/builtin-floating-point.c b/clang/test/CIR/CodeGen/builtin-floating-point.c
index 0b037714247b..5557cb8ad3bc 100644
--- a/clang/test/CIR/CodeGen/builtin-floating-point.c
+++ b/clang/test/CIR/CodeGen/builtin-floating-point.c
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -ffast-math -fclangir-enable -emit-cir %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple aarch64-apple-darwin-macho -ffast-math -fclangir-enable -emit-cir %s -o - | FileCheck %s --check-prefix=AARCH64
 
 // ceil
 
@@ -14,15 +15,16 @@ double my_ceil(double f) {
   // CHECK: {{.+}} = cir.ceil {{.+}} : !cir.double
 }
 
-// long double my_ceill(long double f) {
-//   return __builtin_ceill(f);
-//   // DISABLED-CHECK: cir.func @my_ceill
-//   // DISABLED-CHECK: {{.+}} = cir.ceil {{.+}} : f80
-// }
+long double my_ceill(long double f) {
+  return __builtin_ceill(f);
+  // CHECK: cir.func @my_ceill
+  // CHECK: {{.+}} = cir.ceil {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.ceil {{.+}} : !cir.long_double<!cir.double>
+}
 
 float ceilf(float);
 double ceil(double);
-// long double ceill(long double);
+long double ceill(long double);
 
 float call_ceilf(float f) {
   return ceilf(f);
@@ -36,11 +38,12 @@ double call_ceil(double f) {
   // CHECK: {{.+}} = cir.ceil {{.+}} : !cir.double
 }
 
-// long double call_ceill(long double f) {
-//   return ceill(f);
-//   // DISABLED-CHECK: cir.func @call_ceill
-//   // DISABLED-CHECK: {{.+}} = cir.ceil {{.+}} : f80
-// }
+long double call_ceill(long double f) {
+  return ceill(f);
+  // CHECK: cir.func @call_ceill
+  // CHECK: {{.+}} = cir.ceil {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.ceil {{.+}} : !cir.long_double<!cir.double>
+}
 
 // cos
 
@@ -56,15 +59,16 @@ double my_cos(double f) {
   // CHECK: {{.+}} = cir.cos {{.+}} : !cir.double
 }
 
-// long double my_cosl(long double f) {
-//   return __builtin_cosl(f);
-//   // DISABLED-CHECK: cir.func @my_cosl
-//   // DISABLED-CHECK: {{.+}} = cir.cos {{.+}} : f80
-// }
+long double my_cosl(long double f) {
+  return __builtin_cosl(f);
+  // CHECK: cir.func @my_cosl
+  // CHECK: {{.+}} = cir.cos {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.cos {{.+}} : !cir.long_double<!cir.double>
+}
 
 float cosf(float);
 double cos(double);
-// long double cosl(long double);
+long double cosl(long double);
 
 float call_cosf(float f) {
   return cosf(f);
@@ -78,11 +82,12 @@ double call_cos(double f) {
   // CHECK: {{.+}} = cir.cos {{.+}} : !cir.double
 }
 
-// long double call_cosl(long double f) {
-//   return cosl(f);
-//   // DISABLED-CHECK: cir.func @call_cosl
-//   // DISABLED-CHECK: {{.+}} = cir.cos {{.+}} : f80
-// }
+long double call_cosl(long double f) {
+  return cosl(f);
+  // CHECK: cir.func @call_cosl
+  // CHECK: {{.+}} = cir.cos {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.cos {{.+}} : !cir.long_double<!cir.double>
+}
 
 // exp
 
@@ -98,15 +103,16 @@ double my_exp(double f) {
   // CHECK: {{.+}} = cir.exp {{.+}} : !cir.double
 }
 
-// long double my_expl(long double f) {
-//   return __builtin_expl(f);
-//   // DISABLED-CHECK: cir.func @my_expl
-//   // DISABLED-CHECK: {{.+}} = cir.exp {{.+}} : f80
-// }
+long double my_expl(long double f) {
+  return __builtin_expl(f);
+  // CHECK: cir.func @my_expl
+  // CHECK: {{.+}} = cir.exp {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.exp {{.+}} : !cir.long_double<!cir.double>
+}
 
 float expf(float);
 double exp(double);
-// long double expl(long double);
+long double expl(long double);
 
 float call_expf(float f) {
   return expf(f);
@@ -120,11 +126,12 @@ double call_exp(double f) {
   // CHECK: {{.+}} = cir.exp {{.+}} : !cir.double
 }
 
-// long double call_expl(long double f) {
-//   return expl(f);
-//   // DISABLED-CHECK: cir.func @call_expl
-//   // DISABLED-CHECK: {{.+}} = cir.exp {{.+}} : f80
-// }
+long double call_expl(long double f) {
+  return expl(f);
+  // CHECK: cir.func @call_expl
+  // CHECK: {{.+}} = cir.exp {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.exp {{.+}} : !cir.long_double<!cir.double>
+}
 
 // exp2
 
@@ -140,15 +147,16 @@ double my_exp2(double f) {
   // CHECK: {{.+}} = cir.exp2 {{.+}} : !cir.double
 }
 
-// long double my_exp2l(long double f) {
-//   return __builtin_exp2l(f);
-//   // DISABLED-CHECK: cir.func @my_exp2l
-//   // DISABLED-CHECK: {{.+}} = cir.exp2 {{.+}} : f80
-// }
+long double my_exp2l(long double f) {
+  return __builtin_exp2l(f);
+  // CHECK: cir.func @my_exp2l
+  // CHECK: {{.+}} = cir.exp2 {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.exp2 {{.+}} : !cir.long_double<!cir.double>
+}
 
 float exp2f(float);
 double exp2(double);
-// long double exp2l(long double);
+long double exp2l(long double);
 
 float call_exp2f(float f) {
   return exp2f(f);
@@ -162,11 +170,12 @@ double call_exp2(double f) {
   // CHECK: {{.+}} = cir.exp2 {{.+}} : !cir.double
 }
 
-// long double call_exp2l(long double f) {
-//   return exp2l(f);
-//   // DISABLED-CHECK: cir.func @call_exp2l
-//   // DISABLED-CHECK: {{.+}} = cir.exp2 {{.+}} : f80
-// }
+long double call_exp2l(long double f) {
+  return exp2l(f);
+  // CHECK: cir.func @call_exp2l
+  // CHECK: {{.+}} = cir.exp2 {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.exp2 {{.+}} : !cir.long_double<!cir.double>
+}
 
 // floor
 
@@ -182,15 +191,16 @@ double my_floor(double f) {
   // CHECK: {{.+}} = cir.floor {{.+}} : !cir.double
 }
 
-// long double my_floorl(long double f) {
-//   return __builtin_floorl(f);
-//   // DISABLED-CHECK: cir.func @my_floorl
-//   // DISABLED-CHECK: {{.+}} = cir.floor {{.+}} : f80
-// }
+long double my_floorl(long double f) {
+  return __builtin_floorl(f);
+  // CHECK: cir.func @my_floorl
+  // CHECK: {{.+}} = cir.floor {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.floor {{.+}} : !cir.long_double<!cir.double>
+}
 
 float floorf(float);
 double floor(double);
-// long double floorl(long double);
+long double floorl(long double);
 
 float call_floorf(float f) {
   return floorf(f);
@@ -204,11 +214,12 @@ double call_floor(double f) {
   // CHECK: {{.+}} = cir.floor {{.+}} : !cir.double
 }
 
-// long double call_floorl(long double f) {
-//   return floorl(f);
-//   // DISABLED-CHECK: cir.func @call_floorl
-//   // DISABLED-CHECK: {{.+}} = cir.floor {{.+}} : f80
-// }
+long double call_floorl(long double f) {
+  return floorl(f);
+  // CHECK: cir.func @call_floorl
+  // CHECK: {{.+}} = cir.floor {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.floor {{.+}} : !cir.long_double<!cir.double>
+}
 
 // log
 
@@ -224,15 +235,16 @@ double my_log(double f) {
   // CHECK: {{.+}} = cir.log {{.+}} : !cir.double
 }
 
-// long double my_logl(long double f) {
-//   return __builtin_logl(f);
-//   // DISABLED-CHECK: cir.func @my_logl
-//   // DISABLED-CHECK: {{.+}} = cir.log {{.+}} : f80
-// }
+long double my_logl(long double f) {
+  return __builtin_logl(f);
+  // CHECK: cir.func @my_logl
+  // CHECK: {{.+}} = cir.log {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.log {{.+}} : !cir.long_double<!cir.double>
+}
 
 float logf(float);
 double log(double);
-// long double logl(long double);
+long double logl(long double);
 
 float call_logf(float f) {
   return logf(f);
@@ -246,11 +258,12 @@ double call_log(double f) {
   // CHECK: {{.+}} = cir.log {{.+}} : !cir.double
 }
 
-// long double call_logl(long double f) {
-//   return logl(f);
-//   // DISABLED-CHECK: cir.func @call_logl
-//   // DISABLED-CHECK: {{.+}} = cir.log {{.+}} : f80
-// }
+long double call_logl(long double f) {
+  return logl(f);
+  // CHECK: cir.func @call_logl
+  // CHECK: {{.+}} = cir.log {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.log {{.+}} : !cir.long_double<!cir.double>
+}
 
 // log10
 
@@ -266,15 +279,16 @@ double my_log10(double f) {
   // CHECK: {{.+}} = cir.log10 {{.+}} : !cir.double
 }
 
-// long double my_log10l(long double f) {
-//   return __builtin_log10l(f);
-//   // DISABLED-CHECK: cir.func @my_log10l
-//   // DISABLED-CHECK: {{.+}} = cir.log10 {{.+}} : f80
-// }
+long double my_log10l(long double f) {
+  return __builtin_log10l(f);
+  // CHECK: cir.func @my_log10l
+  // CHECK: {{.+}} = cir.log10 {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.log10 {{.+}} : !cir.long_double<!cir.double>
+}
 
 float log10f(float);
 double log10(double);
-// long double log10l(long double);
+long double log10l(long double);
 
 float call_log10f(float f) {
   return log10f(f);
@@ -288,11 +302,12 @@ double call_log10(double f) {
   // CHECK: {{.+}} = cir.log10 {{.+}} : !cir.double
 }
 
-// long double call_log10l(long double f) {
-//   return log10l(f);
-//   // DISABLED-CHECK: cir.func @call_log10l
-//   // DISABLED-CHECK: {{.+}} = cir.log10 {{.+}} : f80
-// }
+long double call_log10l(long double f) {
+  return log10l(f);
+  // CHECK: cir.func @call_log10l
+  // CHECK: {{.+}} = cir.log10 {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.log10 {{.+}} : !cir.long_double<!cir.double>
+}
 
 // log2
 
@@ -308,15 +323,16 @@ double my_log2(double f) {
   // CHECK: {{.+}} = cir.log2 {{.+}} : !cir.double
 }
 
-// long double my_log2l(long double f) {
-//   return __builtin_log2l(f);
-//   // DISABLED-CHECK: cir.func @my_log2l
-//   // DISABLED-CHECK: {{.+}} = cir.log2 {{.+}} : f80
-// }
+long double my_log2l(long double f) {
+  return __builtin_log2l(f);
+  // CHECK: cir.func @my_log2l
+  // CHECK: {{.+}} = cir.log2 {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.log2 {{.+}} : !cir.long_double<!cir.double>
+}
 
 float log2f(float);
 double log2(double);
-// long double log2l(long double);
+long double log2l(long double);
 
 float call_log2f(float f) {
   return log2f(f);
@@ -330,11 +346,12 @@ double call_log2(double f) {
   // CHECK: {{.+}} = cir.log2 {{.+}} : !cir.double
 }
 
-// long double call_log2l(long double f) {
-//   return log2l(f);
-//   // DISABLED-CHECK: cir.func @call_log2l
-//   // DISABLED-CHECK: {{.+}} = cir.log2 {{.+}} : f80
-// }
+long double call_log2l(long double f) {
+  return log2l(f);
+  // CHECK: cir.func @call_log2l
+  // CHECK: {{.+}} = cir.log2 {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.log2 {{.+}} : !cir.long_double<!cir.double>
+}
 
 // nearbyint
 
@@ -350,15 +367,16 @@ double my_nearbyint(double f) {
   // CHECK: {{.+}} = cir.nearbyint {{.+}} : !cir.double
 }
 
-// long double my_nearbyintl(long double f) {
-//   return __builtin_nearbyintl(f);
-//   // DISABLED-CHECK: cir.func @my_nearbyintl
-//   // DISABLED-CHECK: {{.+}} = cir.nearbyint {{.+}} : f80
-// }
+long double my_nearbyintl(long double f) {
+  return __builtin_nearbyintl(f);
+  // CHECK: cir.func @my_nearbyintl
+  // CHECK: {{.+}} = cir.nearbyint {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.nearbyint {{.+}} : !cir.long_double<!cir.double>
+}
 
 float nearbyintf(float);
 double nearbyint(double);
-// long double nearbyintl(long double);
+long double nearbyintl(long double);
 
 float call_nearbyintf(float f) {
   return nearbyintf(f);
@@ -372,11 +390,12 @@ double call_nearbyint(double f) {
   // CHECK: {{.+}} = cir.nearbyint {{.+}} : !cir.double
 }
 
-// long double call_nearbyintl(long double f) {
-//   return nearbyintl(f);
-//   // DISABLED-CHECK: cir.func @call_nearbyintl
-//   // DISABLED-CHECK: {{.+}} = cir.nearbyint {{.+}} : f80
-// }
+long double call_nearbyintl(long double f) {
+  return nearbyintl(f);
+  // CHECK: cir.func @call_nearbyintl
+  // CHECK: {{.+}} = cir.nearbyint {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.nearbyint {{.+}} : !cir.long_double<!cir.double>
+}
 
 // rint
 
@@ -392,15 +411,16 @@ double my_rint(double f) {
   // CHECK: {{.+}} = cir.rint {{.+}} : !cir.double
 }
 
-// long double my_rintl(long double f) {
-//   return __builtin_rintl(f);
-//   // DISABLED-CHECK: cir.func @my_rintl
-//   // DISABLED-CHECK: {{.+}} = cir.rint {{.+}} : f80
-// }
+long double my_rintl(long double f) {
+  return __builtin_rintl(f);
+  // CHECK: cir.func @my_rintl
+  // CHECK: {{.+}} = cir.rint {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.rint {{.+}} : !cir.long_double<!cir.double>
+}
 
 float rintf(float);
 double rint(double);
-// long double rintl(long double);
+long double rintl(long double);
 
 float call_rintf(float f) {
   return rintf(f);
@@ -414,11 +434,12 @@ double call_rint(double f) {
   // CHECK: {{.+}} = cir.rint {{.+}} : !cir.double
 }
 
-// long double call_rintl(long double f) {
-//   return rintl(f);
-//   // DISABLED-CHECK: cir.func @call_rintl
-//   // DISABLED-CHECK: {{.+}} = cir.rint {{.+}} : f80
-// }
+long double call_rintl(long double f) {
+  return rintl(f);
+  // CHECK: cir.func @call_rintl
+  // CHECK: {{.+}} = cir.rint {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.rint {{.+}} : !cir.long_double<!cir.double>
+}
 
 // round
 
@@ -434,15 +455,16 @@ double my_round(double f) {
   // CHECK: {{.+}} = cir.round {{.+}} : !cir.double
 }
 
-// long double my_roundl(long double f) {
-//   return __builtin_roundl(f);
-//   // DISABLED-CHECK: cir.func @my_roundl
-//   // DISABLED-CHECK: {{.+}} = cir.round {{.+}} : f80
-// }
+long double my_roundl(long double f) {
+  return __builtin_roundl(f);
+  // CHECK: cir.func @my_roundl
+  // CHECK: {{.+}} = cir.round {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.round {{.+}} : !cir.long_double<!cir.double>
+}
 
 float roundf(float);
 double round(double);
-// long double roundl(long double);
+long double roundl(long double);
 
 float call_roundf(float f) {
   return roundf(f);
@@ -456,11 +478,12 @@ double call_round(double f) {
   // CHECK: {{.+}} = cir.round {{.+}} : !cir.double
 }
 
-// long double call_roundl(long double f) {
-//   return roundl(f);
-//   // DISABLED-CHECK: cir.func @call_roundl
-//   // DISABLED-CHECK: {{.+}} = cir.round {{.+}} : f80
-// }
+long double call_roundl(long double f) {
+  return roundl(f);
+  // CHECK: cir.func @call_roundl
+  // CHECK: {{.+}} = cir.round {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.round {{.+}} : !cir.long_double<!cir.double>
+}
 
 // sin
 
@@ -476,15 +499,16 @@ double my_sin(double f) {
   // CHECK: {{.+}} = cir.sin {{.+}} : !cir.double
 }
 
-// long double my_sinl(long double f) {
-//   return __builtin_sinl(f);
-//   // DISABLED-CHECK: cir.func @my_sinl
-//   // DISABLED-CHECK: {{.+}} = cir.sin {{.+}} : f80
-// }
+long double my_sinl(long double f) {
+  return __builtin_sinl(f);
+  // CHECK: cir.func @my_sinl
+  // CHECK: {{.+}} = cir.sin {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.sin {{.+}} : !cir.long_double<!cir.double>
+}
 
 float sinf(float);
 double sin(double);
-// long double sinl(long double);
+long double sinl(long double);
 
 float call_sinf(float f) {
   return sinf(f);
@@ -498,11 +522,12 @@ double call_sin(double f) {
   // CHECK: {{.+}} = cir.sin {{.+}} : !cir.double
 }
 
-// long double call_sinl(long double f) {
-//   return sinl(f);
-//   // DISABLED-CHECK: cir.func @call_sinl
-//   // DISABLED-CHECK: {{.+}} = cir.sin {{.+}} : f80
-// }
+long double call_sinl(long double f) {
+  return sinl(f);
+  // CHECK: cir.func @call_sinl
+  // CHECK: {{.+}} = cir.sin {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.sin {{.+}} : !cir.long_double<!cir.double>
+}
 
 // sqrt
 
@@ -518,15 +543,16 @@ double my_sqrt(double f) {
   // CHECK: {{.+}} = cir.sqrt {{.+}} : !cir.double
 }
 
-// long double my_sqrtl(long double f) {
-//   return __builtin_sqrtl(f);
-//   // DISABLED-CHECK: cir.func @my_sqrtl
-//   // DISABLED-CHECK: {{.+}} = cir.sqrt {{.+}} : f80
-// }
+long double my_sqrtl(long double f) {
+  return __builtin_sqrtl(f);
+  // CHECK: cir.func @my_sqrtl
+  // CHECK: {{.+}} = cir.sqrt {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.sqrt {{.+}} : !cir.long_double<!cir.double>
+}
 
 float sqrtf(float);
 double sqrt(double);
-// long double sqrtl(long double);
+long double sqrtl(long double);
 
 float call_sqrtf(float f) {
   return sqrtf(f);
@@ -540,11 +566,12 @@ double call_sqrt(double f) {
   // CHECK: {{.+}} = cir.sqrt {{.+}} : !cir.double
 }
 
-// long double call_sqrtl(long double f) {
-//   return sqrtl(f);
-//   // DISABLED-CHECK: cir.func @call_sqrtl
-//   // DISABLED-CHECK: {{.+}} = cir.sqrt {{.+}} : f80
-// }
+long double call_sqrtl(long double f) {
+  return sqrtl(f);
+  // CHECK: cir.func @call_sqrtl
+  // CHECK: {{.+}} = cir.sqrt {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.sqrt {{.+}} : !cir.long_double<!cir.double>
+}
 
 // trunc
 
@@ -560,15 +587,16 @@ double my_trunc(double f) {
   // CHECK: {{.+}} = cir.trunc {{.+}} : !cir.double
 }
 
-// long double my_truncl(long double f) {
-//   return __builtin_truncl(f);
-//   // DISABLED-CHECK: cir.func @my_truncl
-//   // DISABLED-CHECK: {{.+}} = cir.trunc {{.+}} : f80
-// }
+long double my_truncl(long double f) {
+  return __builtin_truncl(f);
+  // CHECK: cir.func @my_truncl
+  // CHECK: {{.+}} = cir.trunc {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.trunc {{.+}} : !cir.long_double<!cir.double>
+}
 
 float truncf(float);
 double trunc(double);
-// long double truncl(long double);
+long double truncl(long double);
 
 float call_truncf(float f) {
   return truncf(f);
@@ -582,8 +610,9 @@ double call_trunc(double f) {
   // CHECK: {{.+}} = cir.trunc {{.+}} : !cir.double
 }
 
-// long double call_truncl(long double f) {
-//   return truncl(f);
-//   // DISABLED-CHECK: cir.func @call_truncl
-//   // DISABLED-CHECK: {{.+}} = cir.trunc {{.+}} : f80
-// }
+long double call_truncl(long double f) {
+  return truncl(f);
+  // CHECK: cir.func @call_truncl
+  // CHECK: {{.+}} = cir.trunc {{.+}} : !cir.long_double<!cir.f80>
+  // AARCH64: {{.+}} = cir.trunc {{.+}} : !cir.long_double<!cir.double>
+}
diff --git a/clang/test/CIR/CodeGen/types.c b/clang/test/CIR/CodeGen/types.c
index 50bfdfa5fd72..23dac61b7478 100644
--- a/clang/test/CIR/CodeGen/types.c
+++ b/clang/test/CIR/CodeGen/types.c
@@ -14,7 +14,7 @@ unsigned short t5(unsigned short i) { return i; }
 
 float t6(float i) { return i; }
 double t7(double i) { return i; }
-// long double t10(long double i) { return i; }
+long double t10(long double i) { return i; }
 
 void t8(void) {}
 
@@ -30,7 +30,7 @@ bool t9(bool b) { return b; }
 // CHECK: cir.func @t5(%arg0: !u16i loc({{.*}})) -> !u16i
 // CHECK: cir.func @t6(%arg0: !cir.float loc({{.*}})) -> !cir.float
 // CHECK: cir.func @t7(%arg0: !cir.double loc({{.*}})) -> !cir.double
-// DISABLED-CHECK: cir.func @t10(%arg0: f80 loc({{.*}})) -> f80
+// CHECK: cir.func @t10(%arg0: !cir.long_double<!cir.f80> loc({{.*}})) -> !cir.long_double<!cir.f80>
 // CHECK: cir.func @t8()
 
 // CHECK-CPP: cir.func @_Z2t0i(%arg0: !s32i loc({{.*}})) -> !s32i
@@ -41,6 +41,6 @@ bool t9(bool b) { return b; }
 // CHECK-CPP: cir.func @_Z2t5t(%arg0: !u16i loc({{.*}})) -> !u16i
 // CHECK-CPP: cir.func @_Z2t6f(%arg0: !cir.float loc({{.*}})) -> !cir.float
 // CHECK-CPP: cir.func @_Z2t7d(%arg0: !cir.double loc({{.*}})) -> !cir.double
-// DISABLED-CHECK-CPP: cir.func @{{.+}}t10{{.+}}(%arg0: f80 loc({{.*}})) -> f80
+// CHECK-CPP: cir.func @{{.+}}t10{{.+}}(%arg0: !cir.long_double<!cir.f80> loc({{.*}})) -> !cir.long_double<!cir.f80>
 // CHECK-CPP: cir.func @_Z2t8v()
 // CHECK-CPP: cir.func @_Z2t9b(%arg0: !cir.bool loc({{.*}})) -> !cir.bool
diff --git a/clang/test/CIR/IR/invalid.cir b/clang/test/CIR/IR/invalid.cir
index abc24a79bc4b..cedeb2bd652d 100644
--- a/clang/test/CIR/IR/invalid.cir
+++ b/clang/test/CIR/IR/invalid.cir
@@ -1065,6 +1065,13 @@ module {
 
 // -----
 
+// expected-error@+1 {{invalid underlying type for long double}}
+cir.func @bad_long_double(%arg0 : !cir.long_double<!cir.float>) -> () {
+  cir.return
+}
+
+// -----
+
 !s64i = !cir.int<s, 64>
 !s8i = !cir.int<s, 8>
 !u32i = !cir.int<u, 32>
diff --git a/clang/test/CIR/Lowering/float.cir b/clang/test/CIR/Lowering/float.cir
index ea30674ff7fe..463768a35935 100644
--- a/clang/test/CIR/Lowering/float.cir
+++ b/clang/test/CIR/Lowering/float.cir
@@ -9,10 +9,8 @@ module {
     // CHECK: %{{.+}} = llvm.mlir.constant(1.000000e+00 : f32) : f32
     %2 = cir.const(#cir.fp<1.0> : !cir.double) : !cir.double
     // CHECK: %{{.+}} = llvm.mlir.constant(1.000000e+00 : f64) : f64
-    // %3 = cir.const(1.0 : f128) : f128
-    // DISABLED-CHECK: %{{.+}} = llvm.mlir.constant(1.000000e+00 : f128) : f128
-    // %4 = cir.const(1.0 : f80) : f80
-    // DISABLED-CHECK: %{{.+}} = llvm.mlir.constant(1.000000e+00 : f80) : f80
+    %3 = cir.const(#cir.fp<1.0> : !cir.long_double<!cir.f80>) : !cir.long_double<!cir.f80>
+    // CHECK: %{{.+}} = llvm.mlir.constant(1.000000e+00 : f80) : f80
     // %5 = cir.const(1.0 : bf16) : bf16
     // DISABLED-CHECK: %{{.+}} = llvm.mlir.constant(1.000000e+00 : bf16) : bf16
     cir.return