Index: llvm/lib/IR/ConstantFold.cpp
===================================================================
--- llvm/lib/IR/ConstantFold.cpp
+++ llvm/lib/IR/ConstantFold.cpp
@@ -2298,18 +2298,17 @@
       assert(Ty && "Invalid indices for GEP!");
       Type *OrigGEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
       Type *GEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
-      if (VectorType *VT = dyn_cast<VectorType>(C->getType())) {
-        // FIXME: handle scalable vectors (use getElementCount())
-        GEPTy = FixedVectorType::get(
-            OrigGEPTy, cast<FixedVectorType>(VT)->getNumElements());
-      }
+      if (VectorType *VT = dyn_cast<VectorType>(C->getType()))
+        GEPTy = VectorType::get(OrigGEPTy, VT->getElementCount());
+
       // The GEP returns a vector of pointers when one of more of
       // its arguments is a vector.
       for (unsigned i = 0, e = Idxs.size(); i != e; ++i) {
         if (auto *VT = dyn_cast<VectorType>(Idxs[i]->getType())) {
-          // FIXME: handle scalable vectors
-          GEPTy = FixedVectorType::get(
-              OrigGEPTy, cast<FixedVectorType>(VT)->getNumElements());
+          assert((!isa<VectorType>(GEPTy) || isa<ScalableVectorType>(GEPTy) ==
+                                                 isa<ScalableVectorType>(VT)) &&
+                 "Mismatched GEPTy vector types");
+          GEPTy = VectorType::get(OrigGEPTy, VT->getElementCount());
           break;
         }
       }
Index: llvm/test/Transforms/InstSimplify/gep.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/gep.ll
+++ llvm/test/Transforms/InstSimplify/gep.ll
@@ -168,4 +168,12 @@
   ret <vscale x 4 x i32*> %gep
 }
 
+define <vscale x 2 x i64*> @ptr_idx_mix_scalar_scalable_vector() {
+; CHECK-LABEL: @ptr_idx_mix_scalar_scalable_vector(
+; CHECK-NEXT:    ret <vscale x 2 x i64*> zeroinitializer
+;
+  %v = getelementptr [2 x i64], [2 x i64]* null, i64 0, <vscale x 2 x i64> zeroinitializer
+  ret <vscale x 2 x i64*> %v
+}
+
 ; Check ConstantExpr::getGetElementPtr() using ElementCount for size queries - end.