Index: lib/Transforms/Utils/FunctionComparator.cpp
===================================================================
--- lib/Transforms/Utils/FunctionComparator.cpp
+++ lib/Transforms/Utils/FunctionComparator.cpp
@@ -656,6 +656,16 @@
     return cmpNumbers(RMWI->getSyncScopeID(),
                       cast<AtomicRMWInst>(R)->getSyncScopeID());
   }
+  if (const ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(L)) {
+    ArrayRef<int> LMask = SVI->getShuffleMask();
+    ArrayRef<int> RMask = cast<ShuffleVectorInst>(R)->getShuffleMask();
+    if (int Res = cmpNumbers(LMask.size(), RMask.size()))
+      return Res;
+    for (size_t i = 0, e = LMask.size(); i != e; ++i) {
+      if (int Res = cmpNumbers(LMask[i], RMask[i]))
+        return Res;
+    }
+  }
   if (const PHINode *PNL = dyn_cast<PHINode>(L)) {
     const PHINode *PNR = cast<PHINode>(R);
     // Ensure that in addition to the incoming values being identical
Index: test/Transforms/MergeFunc/shufflevector.ll
===================================================================
--- /dev/null
+++ test/Transforms/MergeFunc/shufflevector.ll
@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -mergefunc < %s | FileCheck %s
+
+define internal <2 x i32> @test1(<2 x i32> %v1, <2 x i32> %v2) {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT:    [[X:%.*]] = shufflevector <2 x i32> [[V1:%.*]], <2 x i32> [[V2:%.*]], <2 x i32> <i32 0, i32 1>
+; CHECK-NEXT:    ret <2 x i32> [[X]]
+;
+  %x = shufflevector <2 x i32> %v1, <2 x i32> %v2, <2 x i32> <i32 0, i32 1>
+  ret <2 x i32> %x
+}
+
+; Same mask as test1.
+define internal <2 x i32> @test2(<2 x i32> %v1, <2 x i32> %v2) {
+  %x = shufflevector <2 x i32> %v1, <2 x i32> %v2, <2 x i32> <i32 0, i32 1>
+  ret <2 x i32> %x
+}
+
+; Different mask than test1, don't merge.
+define internal <2 x i32> @test3(<2 x i32> %v1, <2 x i32> %v2) {
+; CHECK-LABEL: @test3(
+; CHECK-NEXT:    [[X:%.*]] = shufflevector <2 x i32> [[V1:%.*]], <2 x i32> [[V2:%.*]], <2 x i32> <i32 1, i32 0>
+; CHECK-NEXT:    ret <2 x i32> [[X]]
+;
+  %x = shufflevector <2 x i32> %v1, <2 x i32> %v2, <2 x i32> <i32 1, i32 0>
+  ret <2 x i32> %x
+}
+
+define void @caller(<2 x i32> %v1, <2 x i32> %v2) {
+; CHECK-LABEL: @caller(
+; CHECK-NEXT:    [[TMP1:%.*]] = call <2 x i32> @test1(<2 x i32> [[V1:%.*]], <2 x i32> [[V2:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call <2 x i32> @test1(<2 x i32> [[V1]], <2 x i32> [[V2]])
+; CHECK-NEXT:    [[TMP3:%.*]] = call <2 x i32> @test3(<2 x i32> [[V1]], <2 x i32> [[V2]])
+; CHECK-NEXT:    ret void
+;
+  call <2 x i32> @test1(<2 x i32> %v1, <2 x i32> %v2)
+  call <2 x i32> @test2(<2 x i32> %v1, <2 x i32> %v2)
+  call <2 x i32> @test3(<2 x i32> %v1, <2 x i32> %v2)
+  ret void
+}