diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index fd6f4ba..0039d1e 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -3837,6 +3837,28 @@
       if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y,
                                            Pred == ICmpInst::ICMP_EQ))
         return V;
+
+    // Test for zero-shift-guard-ops around funnel shifts. These are used to
+    // avoid UB from oversized shifts in raw IR rotate patterns, but the
+    // intrinsics do not have that problem.
+    Value *ShAmt;
+    auto isFsh = m_CombineOr(m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(),
+                                                          m_Value(ShAmt)),
+                             m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X),
+                                                          m_Value(ShAmt)));
+    // (ShAmt != 0) ? fshl(X, *, ShAmt) : X --> fshl(X, *, ShAmt)
+    // (ShAmt != 0) ? fshr(*, X, ShAmt) : X --> fshr(*, X, ShAmt)
+    // (ShAmt == 0) ? fshl(X, *, ShAmt) : X --> X
+    // (ShAmt == 0) ? fshr(*, X, ShAmt) : X --> X
+    if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt)
+      return Pred == ICmpInst::ICMP_NE ? TrueVal : X;
+
+    // (ShAmt == 0) ? X : fshl(X, *, ShAmt) --> fshl(X, *, ShAmt)
+    // (ShAmt == 0) ? X : fshr(*, X, ShAmt) --> fshr(*, X, ShAmt)
+    // (ShAmt != 0) ? X : fshl(X, *, ShAmt) --> X
+    // (ShAmt != 0) ? X : fshr(*, X, ShAmt) --> X
+    if (match(FalseVal, isFsh) && TrueVal == X && CmpLHS == ShAmt)
+      return Pred == ICmpInst::ICMP_EQ ? FalseVal : X;
   }
 
   // Check for other compares that behave like bit test.