diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 66a3c257a76f8..ba804c10127e2 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -7379,6 +7379,8 @@ class BoUpSLP::ShuffleCostEstimator : public BaseShuffleAnalysis {
             continue;
           if (Idx >= static_cast<int>(CommonVF))
             Idx = E1Mask[Idx - CommonVF] + VF;
+          else
+            Idx = E1Mask[Idx];
         }
         CommonVF = VF;
       }
diff --git a/llvm/test/Transforms/SLPVectorizer/X86/shuffle-mask-resized.ll b/llvm/test/Transforms/SLPVectorizer/X86/shuffle-mask-resized.ll
new file mode 100644
index 0000000000000..7d493dac015a9
--- /dev/null
+++ b/llvm/test/Transforms/SLPVectorizer/X86/shuffle-mask-resized.ll
@@ -0,0 +1,45 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -passes=slp-vectorizer -S -mtriple=x86_64-unknown-linux -slp-threshold=-10 < %s | FileCheck %s
+
+define i32 @test() {
+; CHECK-LABEL: define i32 @test() {
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    br label [[BB1:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[TMP0:%.*]] = phi <2 x i32> [ [[TMP5:%.*]], [[BB3:%.*]] ], [ zeroinitializer, [[BB:%.*]] ]
+; CHECK-NEXT:    [[TMP1:%.*]] = shufflevector <2 x i32> [[TMP0]], <2 x i32> poison, <8 x i32> <i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 1, i32 1>
+; CHECK-NEXT:    br i1 false, label [[BB4:%.*]], label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[TMP2:%.*]] = shufflevector <2 x i32> [[TMP0]], <2 x i32> <i32 0, i32 poison>, <2 x i32> <i32 2, i32 1>
+; CHECK-NEXT:    [[TMP3:%.*]] = add <2 x i32> zeroinitializer, [[TMP2]]
+; CHECK-NEXT:    [[TMP4:%.*]] = or <2 x i32> zeroinitializer, [[TMP2]]
+; CHECK-NEXT:    [[TMP5]] = shufflevector <2 x i32> [[TMP3]], <2 x i32> [[TMP4]], <2 x i32> <i32 0, i32 3>
+; CHECK-NEXT:    br label [[BB1]]
+; CHECK:       bb4:
+; CHECK-NEXT:    [[TMP6:%.*]] = phi <8 x i32> [ [[TMP1]], [[BB1]] ]
+; CHECK-NEXT:    ret i32 0
+;
+bb:
+  br label %bb1
+
+bb1:
+  %phi = phi i32 [ %or, %bb3 ], [ 0, %bb ]
+  %phi2 = phi i32 [ %add, %bb3 ], [ 0, %bb ]
+  br i1 false, label %bb4, label %bb3
+
+bb3:
+  %or = or i32 0, %phi
+  %add = add i32 0, 0
+  br label %bb1
+
+bb4:
+  %phi5 = phi i32 [ %phi2, %bb1 ]
+  %phi6 = phi i32 [ %phi2, %bb1 ]
+  %phi7 = phi i32 [ %phi2, %bb1 ]
+  %phi8 = phi i32 [ %phi2, %bb1 ]
+  %phi9 = phi i32 [ %phi2, %bb1 ]
+  %phi10 = phi i32 [ %phi2, %bb1 ]
+  %phi11 = phi i32 [ %phi, %bb1 ]
+  %phi12 = phi i32 [ %phi, %bb1 ]
+  ret i32 0
+}