Index: lib/Analysis/ValueTracking.cpp
===================================================================
--- lib/Analysis/ValueTracking.cpp
+++ lib/Analysis/ValueTracking.cpp
@@ -4581,6 +4581,9 @@
   Value *CmpRHS = CmpI->getOperand(1);
   Value *TrueVal = SI->getTrueValue();
   Value *FalseVal = SI->getFalseValue();
+  assert(SI != TrueVal && SI != FalseVal &&
+         "Trying to match select pattern for select that refers to itself");
+
   FastMathFlags FMF;
   if (isa<FPMathOperator>(CmpI))
     FMF = CmpI->getFastMathFlags();