diff --git a/llvm/include/llvm/Support/MachineValueType.h b/llvm/include/llvm/Support/MachineValueType.h
--- a/llvm/include/llvm/Support/MachineValueType.h
+++ b/llvm/include/llvm/Support/MachineValueType.h
@@ -478,7 +478,7 @@
 
     /// Returns true if the given vector is a power of 2.
     bool isPow2VectorType() const {
-      unsigned NElts = getVectorNumElements();
+      unsigned NElts = getVectorMinNumElements();
       return !(NElts & (NElts - 1));
     }
 
@@ -488,9 +488,10 @@
       if (isPow2VectorType())
         return *this;
 
-      unsigned NElts = getVectorNumElements();
-      unsigned Pow2NElts = 1 << Log2_32_Ceil(NElts);
-      return MVT::getVectorVT(getVectorElementType(), Pow2NElts);
+      ElementCount NElts = getVectorElementCount();
+      unsigned NewMinCount = 1 << Log2_32_Ceil(NElts.getKnownMinValue());
+      NElts = ElementCount::get(NewMinCount, NElts.isScalable());
+      return MVT::getVectorVT(getVectorElementType(), NElts);
     }
 
     /// If this is a vector, return the element type, otherwise return this.
@@ -651,7 +652,8 @@
       }
     }
 
-    unsigned getVectorNumElements() const {
+    /// Given a vector type, return the minimum number of elements it contains.
+    unsigned getVectorMinNumElements() const {
       switch (SimpleTy) {
       default:
         llvm_unreachable("Not a vector MVT!");
@@ -805,12 +807,12 @@
     }
 
     ElementCount getVectorElementCount() const {
-      return ElementCount::get(getVectorNumElements(), isScalableVector());
+      return ElementCount::get(getVectorMinNumElements(), isScalableVector());
     }
 
-    /// Given a vector type, return the minimum number of elements it contains.
-    unsigned getVectorMinNumElements() const {
-      return getVectorElementCount().getKnownMinValue();
+    unsigned getVectorNumElements() const {
+      // TODO: Check that this isn't a scalable vector.
+      return getVectorMinNumElements();
     }
 
     /// Returns the size of the specified MVT in bits.
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -2101,7 +2101,7 @@
       !Subtarget.hasBWI())
     return TypeSplitVector;
 
-  if (VT.getVectorNumElements() != 1 &&
+  if (!VT.isScalableVector() && VT.getVectorNumElements() != 1 &&
       VT.getVectorElementType() != MVT::i1)
     return TypeWidenVector;
 
diff --git a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
--- a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -630,7 +630,7 @@
       return false;
     if (B.getVectorElementType() != P.getVectorElementType())
       return false;
-    return B.getVectorNumElements() < P.getVectorNumElements();
+    return B.getVectorMinNumElements() < P.getVectorMinNumElements();
   };
 
   /// Return true if S has no element (vector type) that T is a sub-vector of,
@@ -696,8 +696,10 @@
   // An actual vector type cannot have 0 elements, so we can treat scalars
   // as zero-length vectors. This way both vectors and scalars can be
   // processed identically.
-  auto NoLength = [](const SmallSet<unsigned,2> &Lengths, MVT T) -> bool {
-    return !Lengths.count(T.isVector() ? T.getVectorNumElements() : 0);
+  auto NoLength = [](const SmallSet<std::pair<bool, unsigned>, 2> &Lengths,
+                     MVT T) -> bool {
+    return !Lengths.count(std::make_pair(
+        T.isScalableVector(), T.isVector() ? T.getVectorMinNumElements() : 0));
   };
 
   SmallVector<unsigned, 4> Modes;
@@ -706,11 +708,13 @@
     TypeSetByHwMode::SetType &VS = V.get(M);
     TypeSetByHwMode::SetType &WS = W.get(M);
 
-    SmallSet<unsigned,2> VN, WN;
+    SmallSet<std::pair<bool, unsigned>, 2> VN, WN;
     for (MVT T : VS)
-      VN.insert(T.isVector() ? T.getVectorNumElements() : 0);
+      VN.insert(std::make_pair(T.isScalableVector(),
+                               T.isVector() ? T.getVectorMinNumElements() : 0));
     for (MVT T : WS)
-      WN.insert(T.isVector() ? T.getVectorNumElements() : 0);
+      WN.insert(std::make_pair(T.isScalableVector(),
+                               T.isVector() ? T.getVectorMinNumElements() : 0));
 
     Changed |= berase_if(VS, std::bind(NoLength, WN, std::placeholders::_1));
     Changed |= berase_if(WS, std::bind(NoLength, VN, std::placeholders::_1));
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
@@ -378,7 +378,7 @@
     MVT VVT = VT;
     if (VVT.isScalableVector())
       Sig.push_back(IIT_SCALABLE_VEC);
-    switch (VVT.getVectorNumElements()) {
+    switch (VVT.getVectorMinNumElements()) {
     default: PrintFatalError("unhandled vector type width in intrinsic!");
     case 1: Sig.push_back(IIT_V1); break;
     case 2: Sig.push_back(IIT_V2); break;