Index: include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
===================================================================
--- include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
+++ include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
@@ -215,6 +215,11 @@
     return *State.MF;
   }
 
+  const MachineFunction &getMF() const {
+    assert(State.MF && "MachineFunction is not set");
+    return *State.MF;
+  }
+
   /// Getter for DebugLoc
   const DebugLoc &getDL() { return State.DL; }
 
@@ -432,6 +437,15 @@
   /// \return The newly created instruction.
   MachineInstrBuilder buildSExt(const DstOp &Res, const SrcOp &Op);
 
+  /// \return The opcode of the extension the target wants to use for boolean
+  /// values.
+  unsigned getBoolExtOp(bool IsVec, bool IsFP) const;
+
+  // Build and insert \p Res = G_ANYEXT \p Op, \p Res = G_SEXT \p Op, or \p Res
+  // = G_ZEXT \p Op depending on how the target wants to extend boolean values.
+  MachineInstrBuilder buildBoolExt(const DstOp &Res, const SrcOp &Op,
+                                   bool IsFP);
+
   /// Build and insert \p Res = G_ZEXT \p Op
   ///
   /// G_ZEXT produces a register of the specified width, with bits 0 to
Index: lib/CodeGen/GlobalISel/LegalizerHelper.cpp
===================================================================
--- lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -843,8 +843,9 @@
       widenScalarSrc(MI, WideTy, 3, TargetOpcode::G_ANYEXT);
       widenScalarDst(MI, WideTy);
     } else {
+      bool IsVec = MRI.getType(MI.getOperand(1).getReg()).isVector();
       // Explicit extension is required here since high bits affect the result.
-      widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_ZEXT);
+      widenScalarSrc(MI, WideTy, 1, MIRBuilder.getBoolExtOp(IsVec, false));
     }
     Observer.changedInstr(MI);
     return Legalized;
Index: lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
===================================================================
--- lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
+++ lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
@@ -17,6 +17,7 @@
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/TargetInstrInfo.h"
+#include "llvm/CodeGen/TargetLowering.h"
 #include "llvm/CodeGen/TargetOpcodes.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
 #include "llvm/IR/DebugInfo.h"
@@ -342,6 +343,25 @@
   return buildInstr(TargetOpcode::G_ZEXT, Res, Op);
 }
 
+unsigned MachineIRBuilder::getBoolExtOp(bool IsVec, bool IsFP) const {
+  const auto *TLI = getMF().getSubtarget().getTargetLowering();
+  switch (TLI->getBooleanContents(IsVec, IsFP)) {
+  case TargetLoweringBase::ZeroOrNegativeOneBooleanContent:
+    return TargetOpcode::G_SEXT;
+  case TargetLoweringBase::ZeroOrOneBooleanContent:
+    return TargetOpcode::G_ZEXT;
+  default:
+    return TargetOpcode::G_ANYEXT;
+  }
+}
+
+MachineInstrBuilder MachineIRBuilder::buildBoolExt(const DstOp &Res,
+                                                   const SrcOp &Op,
+                                                   bool IsFP) {
+  unsigned ExtOp = getBoolExtOp(getMRI()->getType(Op.getReg()).isVector(), IsFP);
+  return buildInstr(ExtOp, Res, Op);
+}
+
 MachineInstrBuilder MachineIRBuilder::buildExtOrTrunc(unsigned ExtOpc,
                                                       const DstOp &Res,
                                                       const SrcOp &Op) {