diff --git a/llvm/include/llvm/IR/Intrinsics.h b/llvm/include/llvm/IR/Intrinsics.h
--- a/llvm/include/llvm/IR/Intrinsics.h
+++ b/llvm/include/llvm/IR/Intrinsics.h
@@ -100,7 +100,7 @@
       Integer, Vector, Pointer, Struct,
       Argument, ExtendArgument, TruncArgument, HalfVecArgument,
       SameVecWidthArgument, PtrToArgument, PtrToElt, VecOfAnyPtrsToElt,
-      VecElementArgument
+      VecElementArgument, ScalableVecArgument
     } Kind;
 
     union {
diff --git a/llvm/include/llvm/IR/IntrinsicsAArch64.td b/llvm/include/llvm/IR/IntrinsicsAArch64.td
--- a/llvm/include/llvm/IR/IntrinsicsAArch64.td
+++ b/llvm/include/llvm/IR/IntrinsicsAArch64.td
@@ -748,3 +748,31 @@
                           Intrinsic<[llvm_i64_ty], [],
                                     [IntrNoMem, IntrHasSideEffects]>;
 }
+
+//===----------------------------------------------------------------------===//
+// SVE
+
+def llvm_nxv2i1_ty  : LLVMType<nxv2i1>;
+def llvm_nxv4i1_ty  : LLVMType<nxv4i1>;
+def llvm_nxv8i1_ty  : LLVMType<nxv8i1>;
+def llvm_nxv16i1_ty : LLVMType<nxv16i1>;
+def llvm_nxv16i8_ty : LLVMType<nxv16i8>;
+def llvm_nxv4i32_ty : LLVMType<nxv4i32>;
+def llvm_nxv2i64_ty : LLVMType<nxv2i64>;
+def llvm_nxv8f16_ty : LLVMType<nxv8f16>;
+def llvm_nxv4f32_ty : LLVMType<nxv4f32>;
+def llvm_nxv2f64_ty : LLVMType<nxv2f64>;
+
+let TargetPrefix = "aarch64" in {  // All intrinsics start with "llvm.aarch64.".
+  // This class of intrinsics are not intended to be useful within LLVM IR but
+  // are instead here to support some of the more regid parts of the ACLE.
+  class Builtin_SVCVT<string name, LLVMType OUT, LLVMType IN>
+  : GCCBuiltin<"__builtin_sve_" # name>,
+    Intrinsic<[OUT], [OUT, llvm_nxv16i1_ty, IN], [IntrNoMem]>;
+}
+
+//
+// Floating-point comparisons
+//
+
+def int_aarch64_sve_fcvtzs_i32f16 : Builtin_SVCVT<"svcvt_s32_f16_m", llvm_nxv4i32_ty, llvm_nxv8f16_ty>;
diff --git a/llvm/include/llvm/Support/ScalableSize.h b/llvm/include/llvm/Support/ScalableSize.h
--- a/llvm/include/llvm/Support/ScalableSize.h
+++ b/llvm/include/llvm/Support/ScalableSize.h
@@ -36,6 +36,9 @@
   bool operator==(const ElementCount& RHS) const {
     return Min == RHS.Min && Scalable == RHS.Scalable;
   }
+  bool operator!=(const ElementCount& RHS) const {
+    return !(*this == RHS);
+  }
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -611,9 +611,11 @@
       Result += "vararg";
     // Ensure nested function types are distinguishable.
     Result += "f";
-  } else if (isa<VectorType>(Ty)) {
-    Result += "v" + utostr(Ty->getVectorNumElements()) +
-      getMangledTypeStr(Ty->getVectorElementType());
+  } else if (VectorType* VTy = dyn_cast<VectorType>(Ty)) {
+    if (VTy->isScalable())
+      Result += "nx";
+    Result += "v" + utostr(VTy->getVectorNumElements()) +
+      getMangledTypeStr(VTy->getVectorElementType());
   } else if (Ty) {
     switch (Ty->getTypeID()) {
     default: llvm_unreachable("Unhandled type");
@@ -700,7 +702,8 @@
   IIT_STRUCT7 = 39,
   IIT_STRUCT8 = 40,
   IIT_F128 = 41,
-  IIT_VEC_ELEMENT = 42
+  IIT_VEC_ELEMENT = 42,
+  IIT_SCALABLE_VEC = 43
 };
 
 static void DecodeIITType(unsigned &NextElt, ArrayRef<unsigned char> Infos,
@@ -871,6 +874,12 @@
                                              ArgInfo));
     return;
   }
+  case IIT_SCALABLE_VEC: {
+    OutputTable.push_back(IITDescriptor::get(IITDescriptor::ScalableVecArgument,
+                                             0));
+    DecodeIITType(NextElt, Infos, OutputTable);
+    return;
+  }
   }
   llvm_unreachable("unhandled");
 }
@@ -968,7 +977,7 @@
     Type *EltTy = DecodeFixedType(Infos, Tys, Context);
     Type *Ty = Tys[D.getArgumentNumber()];
     if (auto *VTy = dyn_cast<VectorType>(Ty))
-      return VectorType::get(EltTy, VTy->getNumElements());
+      return VectorType::get(EltTy, VTy->getElementCount());
     return EltTy;
   }
   case IITDescriptor::PtrToArgument: {
@@ -992,6 +1001,11 @@
   case IITDescriptor::VecOfAnyPtrsToElt:
     // Return the overloaded type (which determines the pointers address space)
     return Tys[D.getOverloadArgNumber()];
+  case IITDescriptor::ScalableVecArgument: {
+    Type *Ty = DecodeFixedType(Infos, Tys, Context);
+    return VectorType::get(Ty->getVectorElementType(),
+                           { Ty->getVectorNumElements(), true });
+  }
   }
   llvm_unreachable("unhandled");
 }
@@ -1191,8 +1205,8 @@
         return true;
       Type *EltTy = Ty;
       if (ThisArgType) {
-        if (ReferenceType->getVectorNumElements() !=
-            ThisArgType->getVectorNumElements())
+        if (ReferenceType->getElementCount() !=
+            ThisArgType->getElementCount())
           return true;
         EltTy = ThisArgType->getVectorElementType();
       }
@@ -1255,6 +1269,13 @@
       auto *ReferenceType = dyn_cast<VectorType>(ArgTys[D.getArgumentNumber()]);
       return !ReferenceType || Ty != ReferenceType->getElementType();
     }
+    case IITDescriptor::ScalableVecArgument: {
+      VectorType *VTy = dyn_cast<VectorType>(Ty);
+      if (!VTy || !VTy->isScalable())
+        return true;
+      return matchIntrinsicType(VTy, Infos, ArgTys, DeferredChecks,
+                                IsDeferredCheck);
+    }
   }
   llvm_unreachable("unhandled");
 }
diff --git a/llvm/test/Verifier/intrinsic-bad-arg-type.ll b/llvm/test/Verifier/intrinsic-bad-arg-type.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Verifier/intrinsic-bad-arg-type.ll
@@ -0,0 +1,10 @@
+; RUN: not opt -S -verify 2>&1 < %s | FileCheck %s
+
+; CHECK: Intrinsic has incorrect argument type!
+; CHECK-NEXT: <vscale x 4 x i32> (<vscale x 4 x i32>*, i32, <4 x i1>, <vscale x 4 x i32>)* @llvm.masked.load.nxv4i32.p0nxv4i32
+
+define <vscale x 4 x i32> @masked_load(<vscale x 4 x i32>* %addr, <4 x i1> %mask, <vscale x 4 x i32> %dst) {
+  %res = call <vscale x 4 x i32> @llvm.masked.load.nxv4i32.p0nxv4i32(<vscale x 4 x i32>* %addr, i32 4, <4 x i1> %mask, <vscale x 4 x i32> %dst)
+  ret <vscale x 4 x i32> %res
+}
+declare <vscale x 4 x i32> @llvm.masked.load.nxv4i32.p0nxv4i32(<vscale x 4 x i32>*, i32, <4 x i1>, <vscale x 4 x i32>)
diff --git a/llvm/unittests/IR/IRBuilderTest.cpp b/llvm/unittests/IR/IRBuilderTest.cpp
--- a/llvm/unittests/IR/IRBuilderTest.cpp
+++ b/llvm/unittests/IR/IRBuilderTest.cpp
@@ -122,6 +122,51 @@
   EXPECT_FALSE(II->hasNoNaNs());
 }
 
+TEST_F(IRBuilderTest, IntrinsicsWithScalableVectors) {
+  IRBuilder<> Builder(BB);
+  CallInst *Call;
+  FunctionType *FTy;
+
+  // Test scalable flag isn't dropped for intrinsic that is explicitly defined
+  // with scalable vectors, e.g. LLVMType<nxv4i32>.
+  Type *SrcVecTy = VectorType::get(Builder.getHalfTy(), 8, true);
+  Type *DstVecTy = VectorType::get(Builder.getInt32Ty(), 4, true);
+  Type *PredTy = VectorType::get(Builder.getInt1Ty(), 16, true);
+
+  SmallVector<Value*, 3> ArgTys;
+  ArgTys.push_back(UndefValue::get(DstVecTy));
+  ArgTys.push_back(UndefValue::get(PredTy));
+  ArgTys.push_back(UndefValue::get(SrcVecTy));
+
+  Call = Builder.CreateIntrinsic(Intrinsic::aarch64_sve_fcvtzs_i32f16, {},
+                                 ArgTys, nullptr, "aarch64.sve.fcvtzs.i32f16");
+  FTy = Call->getFunctionType();
+  EXPECT_EQ(FTy->getReturnType(), DstVecTy);
+  for (unsigned i = 0; i != ArgTys.size(); ++i)
+    EXPECT_EQ(FTy->getParamType(i), ArgTys[i]->getType());
+
+  // Test scalable flag isn't dropped for intrinsic defined with
+  // LLVMScalarOrSameVectorWidth.
+
+  Type *VecTy = VectorType::get(Builder.getInt32Ty(), 4, true);
+  Type *PtrToVecTy = VecTy->getPointerTo();
+  PredTy = VectorType::get(Builder.getInt1Ty(), 4, true);
+
+  ArgTys.clear();
+  ArgTys.push_back(UndefValue::get(PtrToVecTy));
+  ArgTys.push_back(UndefValue::get(Builder.getInt32Ty()));
+  ArgTys.push_back(UndefValue::get(PredTy));
+  ArgTys.push_back(UndefValue::get(VecTy));
+
+  Call = Builder.CreateIntrinsic(Intrinsic::masked_load,
+                                 {VecTy, PtrToVecTy}, ArgTys,
+                                 nullptr, "masked.load");
+  FTy = Call->getFunctionType();
+  EXPECT_EQ(FTy->getReturnType(), VecTy);
+  for (unsigned i = 0; i != ArgTys.size(); ++i)
+    EXPECT_EQ(FTy->getParamType(i), ArgTys[i]->getType());
+}
+
 TEST_F(IRBuilderTest, ConstrainedFP) {
   IRBuilder<> Builder(BB);
   Value *V;
diff --git a/llvm/utils/TableGen/IntrinsicEmitter.cpp b/llvm/utils/TableGen/IntrinsicEmitter.cpp
--- a/llvm/utils/TableGen/IntrinsicEmitter.cpp
+++ b/llvm/utils/TableGen/IntrinsicEmitter.cpp
@@ -220,7 +220,8 @@
   IIT_STRUCT7 = 39,
   IIT_STRUCT8 = 40,
   IIT_F128 = 41,
-  IIT_VEC_ELEMENT = 42
+  IIT_VEC_ELEMENT = 42,
+  IIT_SCALABLE_VEC = 43
 };
 
 static void EncodeFixedValueType(MVT::SimpleValueType VT,
@@ -339,6 +340,8 @@
 
   if (MVT(VT).isVector()) {
     MVT VVT = VT;
+    if (VVT.isScalableVector())
+      Sig.push_back(IIT_SCALABLE_VEC);
     switch (VVT.getVectorNumElements()) {
     default: PrintFatalError("unhandled vector type width in intrinsic!");
     case 1: Sig.push_back(IIT_V1); break;