diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -2638,9 +2638,14 @@
       }
 
       // We don't combine GEPs with non-constant indexes.
+      Type *Ty1 = VL0->getOperand(1)->getType();
       for (Value *V : VL) {
         auto Op = cast<Instruction>(V)->getOperand(1);
-        if (!isa<ConstantInt>(Op)) {
+        if (!isa<ConstantInt>(Op) ||
+            (Op->getType() != Ty1 &&
+             Op->getType()->getScalarSizeInBits() >
+                 DL->getIndexSizeInBits(
+                     V->getType()->getPointerAddressSpace()))) {
           LLVM_DEBUG(dbgs()
                      << "SLP: not-vectorizable GEP (non-constant indexes).\n");
           BS.cancelScheduling(VL, VL0);
@@ -4156,7 +4161,22 @@
       std::vector<Value *> OpVecs;
       for (int j = 1, e = cast<GetElementPtrInst>(VL0)->getNumOperands(); j < e;
            ++j) {
-        Value *OpVec = vectorizeTree(E->getOperand(j));
+        ValueList &VL = E->getOperand(j);
+        // Need to cast all elements to the same type before vectorization to
+        // avoid crash.
+        Type *VL0Ty = VL0->getOperand(j)->getType();
+        Type *Ty = llvm::all_of(
+                       VL, [VL0Ty](Value *V) { return VL0Ty == V->getType(); })
+                       ? VL0Ty
+                       : DL->getIndexType(cast<GetElementPtrInst>(VL0)
+                                              ->getPointerOperandType()
+                                              ->getScalarType());
+        for (Value *&V : VL) {
+          auto *CI = cast<ConstantInt>(V);
+          V = ConstantExpr::getIntegerCast(CI, Ty,
+                                           CI->getValue().isSignBitSet());
+        }
+        Value *OpVec = vectorizeTree(VL);
         OpVecs.push_back(OpVec);
       }
 
diff --git a/llvm/test/Transforms/SLPVectorizer/X86/crash_gep.ll b/llvm/test/Transforms/SLPVectorizer/X86/crash_gep.ll
--- a/llvm/test/Transforms/SLPVectorizer/X86/crash_gep.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/crash_gep.ll
@@ -29,3 +29,26 @@
   store i64 %2, i64* %add.ptr, align 8
   ret i32 undef
 }
+
+define void @PR43799() {
+; CHECK-LABEL: @PR43799(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[BODY:%.*]]
+; CHECK:       body:
+; CHECK-NEXT:    br label [[BODY]]
+; CHECK:       epilog:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %body
+
+body:
+  %p.1.i19 = phi i8* [ undef, %entry ], [ %incdec.ptr.i.7, %body ]
+  %lsr.iv17 = phi i8* [ undef, %entry ], [ %scevgep113.7, %body ]
+  %incdec.ptr.i.7 = getelementptr inbounds i8, i8* undef, i32 1
+  %scevgep113.7 = getelementptr i8, i8* undef, i64 1
+  br label %body
+
+epilog:
+  ret void
+}