diff --git a/llvm/include/llvm/CodeGen/ReachingDefAnalysis.h b/llvm/include/llvm/CodeGen/ReachingDefAnalysis.h
--- a/llvm/include/llvm/CodeGen/ReachingDefAnalysis.h
+++ b/llvm/include/llvm/CodeGen/ReachingDefAnalysis.h
@@ -55,7 +55,7 @@
   /// The first instruction in each basic block is 0.
   int CurInstr;
 
-  /// Maps instructions to their instruction Ids, relative to the begining of
+  /// Maps instructions to their instruction Ids, relative to the beginning of
   /// their basic blocks.
   DenseMap<MachineInstr *, int> InstIds;
 
diff --git a/llvm/lib/CodeGen/ReachingDefAnalysis.cpp b/llvm/lib/CodeGen/ReachingDefAnalysis.cpp
--- a/llvm/lib/CodeGen/ReachingDefAnalysis.cpp
+++ b/llvm/lib/CodeGen/ReachingDefAnalysis.cpp
@@ -215,9 +215,11 @@
     return nullptr;
 
   for (auto &MI : *MBB) {
-    if (InstIds.count(&MI) && InstIds.lookup(&MI) == InstId)
+    auto F = InstIds.find(&MI);
+    if (F != InstIds.end() && F->second == InstId)
       return &MI;
   }
+
   return nullptr;
 }