diff --git a/llvm/include/llvm/CodeGen/ValueTypes.h b/llvm/include/llvm/CodeGen/ValueTypes.h
--- a/llvm/include/llvm/CodeGen/ValueTypes.h
+++ b/llvm/include/llvm/CodeGen/ValueTypes.h
@@ -76,9 +76,7 @@
       MVT M = MVT::getVectorVT(VT.V, NumElements, IsScalable);
       if (M.SimpleTy != MVT::INVALID_SIMPLE_VALUE_TYPE)
         return M;
-
-      assert(!IsScalable && "We don't support extended scalable types yet");
-      return getExtendedVectorVT(Context, VT, NumElements);
+      return getExtendedVectorVT(Context, VT, NumElements, IsScalable);
     }
 
     /// Returns the EVT that represents a vector EC.Min elements in length,
@@ -87,19 +85,15 @@
       MVT M = MVT::getVectorVT(VT.V, EC);
       if (M.SimpleTy != MVT::INVALID_SIMPLE_VALUE_TYPE)
         return M;
-      assert (!EC.Scalable && "We don't support extended scalable types yet");
-      return getExtendedVectorVT(Context, VT, EC.Min);
+      return getExtendedVectorVT(Context, VT, EC);
     }
 
     /// Return a vector with the same number of elements as this vector, but
     /// with the element type converted to an integer type with the same
     /// bitwidth.
     EVT changeVectorElementTypeToInteger() const {
-      if (!isSimple()) {
-        assert (!isScalableVector() &&
-                "We don't support extended scalable types yet");
+      if (!isSimple())
         return changeExtendedVectorElementTypeToInteger();
-      }
       MVT EltTy = getSimpleVT().getVectorElementType();
       unsigned BitWidth = EltTy.getSizeInBits();
       MVT IntTy = MVT::getIntegerVT(BitWidth);
@@ -156,12 +150,7 @@
     /// Return true if this is a vector type where the runtime
     /// length is machine dependent
     bool isScalableVector() const {
-      // FIXME: We don't support extended scalable types yet, because the
-      // matching IR type doesn't exist. Once it has been added, this can
-      // be changed to call isExtendedScalableVector.
-      if (!isSimple())
-        return false;
-      return V.isScalableVector();
+      return isSimple() ? V.isScalableVector() : isExtendedScalableVector();
     }
 
     bool isFixedLengthVector() const {
@@ -300,9 +289,7 @@
       if (isSimple())
         return V.getVectorElementCount();
 
-      assert(!isScalableVector() &&
-             "We don't support extended scalable types yet");
-      return {getExtendedVectorNumElements(), false};
+      return {getExtendedVectorNumElements(), isExtendedScalableVector()};
     }
 
     /// Return the size of the specified value type in bits.
@@ -443,8 +430,10 @@
     EVT changeExtendedTypeToInteger() const;
     EVT changeExtendedVectorElementTypeToInteger() const;
     static EVT getExtendedIntegerVT(LLVMContext &C, unsigned BitWidth);
-    static EVT getExtendedVectorVT(LLVMContext &C, EVT VT,
-                                   unsigned NumElements);
+    static EVT getExtendedVectorVT(LLVMContext &C, EVT VT, unsigned NumElements,
+                                   bool IsScalable);
+    static EVT getExtendedVectorVT(LLVMContext &Context, EVT VT,
+                                   ElementCount EC);
     bool isExtendedFloatingPoint() const LLVM_READONLY;
     bool isExtendedInteger() const LLVM_READONLY;
     bool isExtendedScalarInteger() const LLVM_READONLY;
@@ -458,8 +447,10 @@
     bool isExtended1024BitVector() const LLVM_READONLY;
     bool isExtended2048BitVector() const LLVM_READONLY;
     bool isExtendedFixedLengthVector() const LLVM_READONLY;
+    bool isExtendedScalableVector() const LLVM_READONLY;
     EVT getExtendedVectorElementType() const;
     unsigned getExtendedVectorNumElements() const LLVM_READONLY;
+    ElementCount getExtendedVectorElementCount() const LLVM_READONLY;
     TypeSize getExtendedSizeInBits() const LLVM_READONLY;
   };
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -415,10 +415,13 @@
     // Build a vector with BUILD_VECTOR or CONCAT_VECTORS from the
     // intermediate operands.
     EVT BuiltVectorTy =
-        EVT::getVectorVT(*DAG.getContext(), IntermediateVT.getScalarType(),
-                         (IntermediateVT.isVector()
-                              ? IntermediateVT.getVectorNumElements() * NumParts
-                              : NumIntermediates));
+        IntermediateVT.isVector()
+            ? EVT::getVectorVT(
+                  *DAG.getContext(), IntermediateVT.getScalarType(),
+                  IntermediateVT.getVectorElementCount() * NumParts)
+            : EVT::getVectorVT(*DAG.getContext(),
+                               IntermediateVT.getScalarType(),
+                               NumIntermediates);
     Val = DAG.getNode(IntermediateVT.isVector() ? ISD::CONCAT_VECTORS
                                                 : ISD::BUILD_VECTOR,
                       DL, BuiltVectorTy, Ops);
diff --git a/llvm/lib/CodeGen/ValueTypes.cpp b/llvm/lib/CodeGen/ValueTypes.cpp
--- a/llvm/lib/CodeGen/ValueTypes.cpp
+++ b/llvm/lib/CodeGen/ValueTypes.cpp
@@ -22,7 +22,8 @@
 EVT EVT::changeExtendedVectorElementTypeToInteger() const {
   LLVMContext &Context = LLVMTy->getContext();
   EVT IntTy = getIntegerVT(Context, getScalarSizeInBits());
-  return getVectorVT(Context, IntTy, getVectorNumElements());
+  return getVectorVT(Context, IntTy, getVectorNumElements(),
+                     isScalableVector());
 }
 
 EVT EVT::getExtendedIntegerVT(LLVMContext &Context, unsigned BitWidth) {
@@ -32,10 +33,19 @@
   return VT;
 }
 
-EVT EVT::getExtendedVectorVT(LLVMContext &Context, EVT VT,
-                             unsigned NumElements) {
+EVT EVT::getExtendedVectorVT(LLVMContext &Context, EVT VT, unsigned NumElements,
+                             bool IsScalable) {
   EVT ResultVT;
-  ResultVT.LLVMTy = VectorType::get(VT.getTypeForEVT(Context), NumElements);
+  ResultVT.LLVMTy =
+      VectorType::get(VT.getTypeForEVT(Context), NumElements, IsScalable);
+  assert(ResultVT.isExtended() && "Type is not extended!");
+  return ResultVT;
+}
+
+EVT EVT::getExtendedVectorVT(LLVMContext &Context, EVT VT, ElementCount EC) {
+  EVT ResultVT;
+  ResultVT.LLVMTy =
+      VectorType::get(VT.getTypeForEVT(Context), {EC.Min, EC.Scalable});
   assert(ResultVT.isExtended() && "Type is not extended!");
   return ResultVT;
 }
@@ -96,6 +106,10 @@
   return isExtendedVector() && !cast<VectorType>(LLVMTy)->isScalable();
 }
 
+bool EVT::isExtendedScalableVector() const {
+  return isExtendedVector() && cast<VectorType>(LLVMTy)->isScalable();
+}
+
 EVT EVT::getExtendedVectorElementType() const {
   assert(isExtended() && "Type is not extended!");
   return EVT::getEVT(cast<VectorType>(LLVMTy)->getElementType());
@@ -106,6 +120,11 @@
   return cast<VectorType>(LLVMTy)->getNumElements();
 }
 
+ElementCount EVT::getExtendedVectorElementCount() const {
+  assert(isExtended() && "Type is not extended!");
+  return cast<VectorType>(LLVMTy)->getElementCount();
+}
+
 TypeSize EVT::getExtendedSizeInBits() const {
   assert(isExtended() && "Type is not extended!");
   if (IntegerType *ITy = dyn_cast<IntegerType>(LLVMTy))