diff --git a/llvm/include/llvm/Analysis/IVDescriptors.h b/llvm/include/llvm/Analysis/IVDescriptors.h
--- a/llvm/include/llvm/Analysis/IVDescriptors.h
+++ b/llvm/include/llvm/Analysis/IVDescriptors.h
@@ -322,7 +322,9 @@
 
   /// Returns true if \p Phi is an induction in the loop \p L. If \p Phi is an
   /// induction, the induction descriptor \p D will contain the data describing
-  /// this induction. If by some other means the caller has a better SCEV
+  /// this induction. Since Induction Phis can only be present inside loop
+  /// headers, the function will assert if it is passed a Phi whose parent is
+  /// not the loop header. If by some other means the caller has a better SCEV
   /// expression for \p Phi than the one returned by the ScalarEvolution
   /// analysis, it can be passed through \p Expr. If the def-use chain
   /// associated with the phi includes casts (that we know we can ignore
diff --git a/llvm/lib/Analysis/IVDescriptors.cpp b/llvm/lib/Analysis/IVDescriptors.cpp
--- a/llvm/lib/Analysis/IVDescriptors.cpp
+++ b/llvm/lib/Analysis/IVDescriptors.cpp
@@ -1484,6 +1484,12 @@
     return false;
   }
 
+  // This function assumes that InductionPhi is called only on Phi nodes
+  // present inside loop headers. Check for the same, and throw an assert if
+  // the current Phi is not present inside the loop header.
+  assert(Phi->getParent() == AR->getLoop()->getHeader()
+    && "Invalid Phi node, not present in loop header");
+
   Value *StartValue =
       Phi->getIncomingValueForBlock(AR->getLoop()->getLoopPreheader());