diff --git a/source/opt/dead_insert_elim_pass.cpp b/source/opt/dead_insert_elim_pass.cpp
index 55f4efe7b..ed0c7b8fe 100644
--- a/source/opt/dead_insert_elim_pass.cpp
+++ b/source/opt/dead_insert_elim_pass.cpp
@@ -65,9 +65,9 @@ uint32_t DeadInsertElimPass::NumComponents(ir::Instruction* typeInst) {
   }
 }
 
-void DeadInsertElimPass::MarkInsertChain(ir::Instruction* insertChain,
-                                         std::vector<uint32_t>* pExtIndices,
-                                         uint32_t extOffset) {
+void DeadInsertElimPass::MarkInsertChain(
+    ir::Instruction* insertChain, std::vector<uint32_t>* pExtIndices,
+    uint32_t extOffset, std::unordered_set<uint32_t>* visited_phis) {
   // Not currently optimizing array inserts.
   ir::Instruction* typeInst = get_def_use_mgr()->GetDef(insertChain->type_id());
   if (typeInst->opcode() == SpvOpTypeArray) return;
@@ -84,7 +84,8 @@ void DeadInsertElimPass::MarkInsertChain(ir::Instruction* insertChain,
       for (uint32_t i = 0; i < cnum; i++) {
         extIndices.clear();
         extIndices.push_back(i);
-        MarkInsertChain(insertChain, &extIndices, 0);
+        std::unordered_set<uint32_t> sub_visited_phis;
+        MarkInsertChain(insertChain, &extIndices, 0, &sub_visited_phis);
       }
       return;
     }
@@ -101,14 +102,18 @@ void DeadInsertElimPass::MarkInsertChain(ir::Instruction* insertChain,
     if (pExtIndices == nullptr) {
       liveInserts_.insert(insInst->result_id());
       uint32_t objId = insInst->GetSingleWordInOperand(kInsertObjectIdInIdx);
-      MarkInsertChain(get_def_use_mgr()->GetDef(objId), nullptr, 0);
+      std::unordered_set<uint32_t> obj_visited_phis;
+      MarkInsertChain(get_def_use_mgr()->GetDef(objId), nullptr, 0,
+                      &obj_visited_phis);
     }
     // If extract indices match insert, we are done. Mark insert and
     // inserted object.
     else if (ExtInsMatch(*pExtIndices, insInst, extOffset)) {
       liveInserts_.insert(insInst->result_id());
       uint32_t objId = insInst->GetSingleWordInOperand(kInsertObjectIdInIdx);
-      MarkInsertChain(get_def_use_mgr()->GetDef(objId), nullptr, 0);
+      std::unordered_set<uint32_t> obj_visited_phis;
+      MarkInsertChain(get_def_use_mgr()->GetDef(objId), nullptr, 0,
+                      &obj_visited_phis);
       break;
     }
     // If non-matching intersection, mark insert
@@ -119,15 +124,18 @@ void DeadInsertElimPass::MarkInsertChain(ir::Instruction* insertChain,
       uint32_t numInsertIndices = insInst->NumInOperands() - 2;
       if (pExtIndices->size() - extOffset > numInsertIndices) {
         uint32_t objId = insInst->GetSingleWordInOperand(kInsertObjectIdInIdx);
+        std::unordered_set<uint32_t> obj_visited_phis;
         MarkInsertChain(get_def_use_mgr()->GetDef(objId), pExtIndices,
-                        extOffset + numInsertIndices);
+                        extOffset + numInsertIndices, &obj_visited_phis);
         break;
       }
       // If fewer extract indices than insert, also mark inserted object and
       // continue up chain.
       else {
         uint32_t objId = insInst->GetSingleWordInOperand(kInsertObjectIdInIdx);
-        MarkInsertChain(get_def_use_mgr()->GetDef(objId), nullptr, 0);
+        std::unordered_set<uint32_t> obj_visited_phis;
+        MarkInsertChain(get_def_use_mgr()->GetDef(objId), nullptr, 0,
+                        &obj_visited_phis);
       }
     }
     // Get next insert in chain
@@ -139,14 +147,8 @@ void DeadInsertElimPass::MarkInsertChain(ir::Instruction* insertChain,
   if (insInst->opcode() != SpvOpPhi) return;
   // Mark phi visited to prevent potential infinite loop. If phi is already
   // visited, return to avoid infinite loop.
-  auto iter = visitedPhis_.find(insInst->result_id());
-  if (iter == visitedPhis_.end()) {
-    iter = visitedPhis_.emplace(insInst->result_id(), true).first;
-  } else if (iter->second) {
-    return;
-  } else {
-    iter->second = true;
-  }
+  if (visited_phis->count(insInst->result_id()) != 0) return;
+  visited_phis->insert(insInst->result_id());
 
   // Phis may have duplicate inputs values for different edges, prune incoming
   // ids lists before recursing.
@@ -158,11 +160,8 @@ void DeadInsertElimPass::MarkInsertChain(ir::Instruction* insertChain,
   auto new_end = std::unique(ids.begin(), ids.end());
   for (auto id_iter = ids.begin(); id_iter != new_end; ++id_iter) {
     ir::Instruction* pi = get_def_use_mgr()->GetDef(*id_iter);
-    MarkInsertChain(pi, pExtIndices, extOffset);
+    MarkInsertChain(pi, pExtIndices, extOffset, visited_phis);
   }
-
-  // Unmark phi when done visiting.
-  iter->second = false;
 }
 
 bool DeadInsertElimPass::EliminateDeadInserts(ir::Function* func) {
@@ -216,11 +215,12 @@ bool DeadInsertElimPass::EliminateDeadInsertsOnePass(ir::Function* func) {
               ++icnt;
             });
             // Mark all inserts in chain that intersect with extract
-            MarkInsertChain(&*ii, &extIndices, 0);
+            std::unordered_set<uint32_t> visited_phis;
+            MarkInsertChain(&*ii, &extIndices, 0, &visited_phis);
           } break;
           default: {
             // Mark inserts in chain for all components
-            MarkInsertChain(&*ii, nullptr, 0);
+            MarkInsertChain(&*ii, nullptr, 0, nullptr);
           } break;
         }
       });
diff --git a/source/opt/dead_insert_elim_pass.h b/source/opt/dead_insert_elim_pass.h
index 97a725d9c..f7ee46a83 100644
--- a/source/opt/dead_insert_elim_pass.h
+++ b/source/opt/dead_insert_elim_pass.h
@@ -50,7 +50,8 @@ class DeadInsertElimPass : public MemPass {
   // index at |extOffset|. Chains are composed solely of Inserts and Phis.
   // Mark all inserts in chain if |extIndices| is nullptr.
   void MarkInsertChain(ir::Instruction* insertChain,
-                       std::vector<uint32_t>* extIndices, uint32_t extOffset);
+                       std::vector<uint32_t>* extIndices, uint32_t extOffset,
+                       std::unordered_set<uint32_t>* visited_phis);
 
   // Perform EliminateDeadInsertsOnePass(|func|) until no modification is
   // made. Return true if modified.