diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 33ada3655dc73..f160dde25d26b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -8627,6 +8627,10 @@ calculateByteProvider(SDValue Op, unsigned Index, unsigned Depth,
     if (NarrowBitWidth % 8 != 0)
       return std::nullopt;
     uint64_t NarrowByteWidth = NarrowBitWidth / 8;
+    // EXTRACT_VECTOR_ELT can extend the element type to the width of the return
+    // type, leaving the high bits undefined.
+    if (Index >= NarrowByteWidth)
+      return std::nullopt;
 
     // Check to see if the position of the element in the vector corresponds
     // with the byte we are trying to provide for. In the case of a vector of
diff --git a/llvm/test/CodeGen/RISCV/rvv/pr83920.ll b/llvm/test/CodeGen/RISCV/rvv/pr83920.ll
new file mode 100644
index 0000000000000..319f0bd9ef1cd
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/rvv/pr83920.ll
@@ -0,0 +1,16 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+; RUN: llc < %s -mtriple=riscv64 -mattr=+v | FileCheck %s
+
+define i8 @or_load_combine(ptr %p) {
+; CHECK-LABEL: or_load_combine:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vsetivli zero, 2, e8, mf8, ta, ma
+; CHECK-NEXT:    vle8.v v8, (a0)
+; CHECK-NEXT:    vmv.x.s a0, v8
+; CHECK-NEXT:    ori a0, a0, 1
+; CHECK-NEXT:    ret
+  %load = load <2 x i8>, ptr %p
+  %extract = extractelement <2 x i8> %load, i64 0
+  %or = or i8 %extract, 1
+  ret i8 %or
+}