diff --git a/llvm/lib/Target/DirectX/DXILDataScalarization.cpp b/llvm/lib/Target/DirectX/DXILDataScalarization.cpp
index c97c604fdbf77..a98a34f0402e1 100644
--- a/llvm/lib/Target/DirectX/DXILDataScalarization.cpp
+++ b/llvm/lib/Target/DirectX/DXILDataScalarization.cpp
@@ -302,7 +302,7 @@ bool DataScalarizerVisitor::visitExtractElementInst(ExtractElementInst &EEI) {
 
 bool DataScalarizerVisitor::visitGetElementPtrInst(GetElementPtrInst &GEPI) {
   Value *PtrOperand = GEPI.getPointerOperand();
-  Type *OrigGEPType = GEPI.getPointerOperandType();
+  Type *OrigGEPType = GEPI.getSourceElementType();
   Type *NewGEPType = OrigGEPType;
   bool NeedsTransform = false;
 
@@ -319,6 +319,12 @@ bool DataScalarizerVisitor::visitGetElementPtrInst(GetElementPtrInst &GEPI) {
     }
   }
 
+  // The new GEP type will be the flattened type unless the original GEP is
+  // an i8 GEP which will be handled by the DXIL legalization pass instead
+  if (OrigGEPType->isIntegerTy(8)) {
+    NewGEPType = OrigGEPType;
+  }
+
   // Note: We bail if this isn't a gep touched via alloca or global
   // transformations
   if (!NeedsTransform)
diff --git a/llvm/test/CodeGen/DirectX/issue-145370-scalarize-i8-gep.ll b/llvm/test/CodeGen/DirectX/issue-145370-scalarize-i8-gep.ll
new file mode 100644
index 0000000000000..2a0fa96eb7e9a
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/issue-145370-scalarize-i8-gep.ll
@@ -0,0 +1,16 @@
+; RUN: opt -S -passes='dxil-data-scalarization' -mtriple=dxil-pc-shadermodel6.3-library %s | FileCheck %s --check-prefixes=SCHECK,CHECK
+; RUN: opt -S -passes='dxil-data-scalarization,dxil-flatten-arrays,function(dxil-legalize)' -mtriple=dxil-pc-shadermodel6.3-library %s | FileCheck %s --check-prefixes=LCHECK,CHECK
+
+; SCHECK: @g.scalarized = local_unnamed_addr addrspace(3) global [2 x [2 x i32]] zeroinitializer, align 8
+; LCHECK: @g.scalarized.1dim = local_unnamed_addr addrspace(3) global [4 x i32] zeroinitializer, align 8
+@g = local_unnamed_addr addrspace(3) global [2 x <2 x i32>] zeroinitializer, align 8
+
+; CHECK-LABEL: test_store
+define void @test_store(<4 x float> noundef %a) #0 {
+  ; SCHECK: store i32 0, ptr addrspace(3) getelementptr inbounds nuw (i8, ptr addrspace(3) @g.scalarized, i32 12), align 4
+  ; LCHECK: store i32 0, ptr addrspace(3) getelementptr inbounds nuw ([4 x i32], ptr addrspace(3) @g.scalarized.1dim, i32 0, i32 3), align 4
+  store i32 0, ptr addrspace(3) getelementptr inbounds nuw (i8, ptr addrspace(3) @g, i32 12), align 4
+  ret void
+} 
+
+attributes #0 = { convergent norecurse nounwind "hlsl.export"}