diff --git a/llvm/test/TableGen/GlobalISelEmitterVariadic.td b/llvm/test/TableGen/GlobalISelEmitterVariadic.td
new file mode 100644
--- /dev/null
+++ b/llvm/test/TableGen/GlobalISelEmitterVariadic.td
@@ -0,0 +1,55 @@
+// RUN: llvm-tblgen -gen-global-isel -I %p/../../include -I %p/Common %s -o - | FileCheck %s
+
+include "llvm/Target/Target.td"
+include "GlobalISelEmitterCommon.td"
+
+def : GINodeEquiv<G_BUILD_VECTOR, build_vector>;
+
+def ONE : I<(outs GPR32:$dst), (ins GPR32:$src1), []>;
+def TWO : I<(outs GPR32:$dst), (ins GPR32:$src1, GPR32:$src2), []>;
+
+// G_BUILD_VECTOR is guaranteed to have at least one operand, therefore performing a
+// number of operands check is not needed to avoid per-operand checks accessing the
+// MI's operand list out of bounds in this particular pattern. However, we still
+// must perform the check, as a G_BUILD_VECTOR instance with two source operands
+// will pass all checks done by this pattern otherwise, which will lead to a
+// mis-match if this pattern tried first (and it will if it has higher complexity).
+def : Pat<(build_vector GPR32:$src1),
+          (ONE GPR32:$src1)> {
+  let AddedComplexity = 1000;
+}
+
+def : Pat<(build_vector GPR32:$src1, GPR32:$src2),
+          (TWO GPR32:$src1, GPR32:$src2)>;
+
+// CHECK:       GIM_Try, /*On fail goto*//*Label 0*/ [[NEXT_OPCODE_LABEL:[0-9]+]],
+// CHECK-NEXT:    GIM_CheckOpcode, /*MI*/0, TargetOpcode::G_BUILD_VECTOR,
+// CHECK-NEXT:    GIM_Try, /*On fail goto*//*Label 1*/ [[NEXT_NUM_OPERANDS_LABEL_1:[0-9]+]], // Rule ID 0 //
+// CHECK-NEXT:      GIM_CheckNumOperands, /*MI*/0, /*Expected*/2,
+// CHECK-NEXT:      GIM_CheckType, /*MI*/0, /*Op*/0, /*Type*/GILLT_s32,
+// CHECK-NEXT:      GIM_CheckType, /*MI*/0, /*Op*/1, /*Type*/GILLT_s32,
+// CHECK-NEXT:      GIM_CheckRegBankForClass, /*MI*/0, /*Op*/0, /*RC*/MyTarget::GPR32RegClassID,
+// CHECK-NEXT:      GIM_CheckRegBankForClass, /*MI*/0, /*Op*/1, /*RC*/MyTarget::GPR32RegClassID,
+// CHECK-NEXT:      // (build_vector:{ *:[i32] } GPR32:{ *:[i32] }:$src1)  =>  (ONE:{ *:[i32] } GPR32:{ *:[i32] }:$src1)
+// CHECK-NEXT:      GIR_MutateOpcode, /*InsnID*/0, /*RecycleInsnID*/0, /*Opcode*/MyTarget::ONE,
+// CHECK-NEXT:      GIR_ConstrainSelectedInstOperands, /*InsnID*/0,
+// CHECK-NEXT:      // GIR_Coverage, 0,
+// CHECK-NEXT:      GIR_Done,
+// CHECK-NEXT:    // Label 1: @[[NEXT_NUM_OPERANDS_LABEL_1]]
+// CHECK-NEXT:    GIM_Try, /*On fail goto*//*Label 2*/ [[NEXT_NUM_OPERANDS_LABEL_2:[0-9]+]], // Rule ID 1 //
+// CHECK-NEXT:      GIM_CheckNumOperands, /*MI*/0, /*Expected*/3,
+// CHECK-NEXT:      GIM_CheckType, /*MI*/0, /*Op*/0, /*Type*/GILLT_s32,
+// CHECK-NEXT:      GIM_CheckType, /*MI*/0, /*Op*/1, /*Type*/GILLT_s32,
+// CHECK-NEXT:      GIM_CheckType, /*MI*/0, /*Op*/2, /*Type*/GILLT_s32,
+// CHECK-NEXT:      GIM_CheckRegBankForClass, /*MI*/0, /*Op*/0, /*RC*/MyTarget::GPR32RegClassID,
+// CHECK-NEXT:      GIM_CheckRegBankForClass, /*MI*/0, /*Op*/1, /*RC*/MyTarget::GPR32RegClassID,
+// CHECK-NEXT:      GIM_CheckRegBankForClass, /*MI*/0, /*Op*/2, /*RC*/MyTarget::GPR32RegClassID,
+// CHECK-NEXT:      // (build_vector:{ *:[i32] } GPR32:{ *:[i32] }:$src1, GPR32:{ *:[i32] }:$src2)  =>  (TWO:{ *:[i32] } GPR32:{ *:[i32] }:$src1, GPR32:{ *:[i32] }:$src2)
+// CHECK-NEXT:      GIR_MutateOpcode, /*InsnID*/0, /*RecycleInsnID*/0, /*Opcode*/MyTarget::TWO,
+// CHECK-NEXT:      GIR_ConstrainSelectedInstOperands, /*InsnID*/0,
+// CHECK-NEXT:      // GIR_Coverage, 1,
+// CHECK-NEXT:      GIR_Done,
+// CHECK-NEXT:    // Label 2: @[[NEXT_NUM_OPERANDS_LABEL_2]]
+// CHECK-NEXT:    GIM_Reject,
+// CHECK-NEXT:  // Label 0: @[[NEXT_OPCODE_LABEL]]
+// CHECK-NEXT:  GIM_Reject,
diff --git a/llvm/utils/TableGen/GlobalISelEmitter.cpp b/llvm/utils/TableGen/GlobalISelEmitter.cpp
--- a/llvm/utils/TableGen/GlobalISelEmitter.cpp
+++ b/llvm/utils/TableGen/GlobalISelEmitter.cpp
@@ -1707,7 +1707,7 @@
   }
 
   StringRef getOpcode() const { return I->TheDef->getName(); }
-  unsigned getNumOperands() const { return I->Operands.size(); }
+  bool isVariadicNumOperands() const { return I->Operands.isVariadic; }
 
   StringRef getOperandType(unsigned OpIdx) const {
     return I->Operands[OpIdx].OperandType;
@@ -2273,7 +2273,7 @@
 
   Stash.push_back(predicates_pop_front());
   if (Stash.back().get() == &OpcMatcher) {
-    if (NumOperandsCheck && OpcMatcher.getNumOperands() < getNumOperands())
+    if (NumOperandsCheck && OpcMatcher.isVariadicNumOperands())
       Stash.emplace_back(
           new InstructionNumOperandsMatcher(InsnVarID, getNumOperands()));
     NumOperandsCheck = false;