diff --git a/llvm/include/llvm/MC/MCObjectStreamer.h b/llvm/include/llvm/MC/MCObjectStreamer.h
--- a/llvm/include/llvm/MC/MCObjectStreamer.h
+++ b/llvm/include/llvm/MC/MCObjectStreamer.h
@@ -38,7 +38,7 @@
   bool EmitEHFrame;
   bool EmitDebugFrame;
   SmallVector<MCSymbol *, 2> PendingLabels;
-  SmallVector<MCSection*, 2> PendingLabelSections;
+  SmallPtrSet<MCSection *, 4> PendingLabelSections;
   unsigned CurSubsectionIdx;
   struct PendingMCFixup {
     const MCSymbol *Sym;
diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -59,12 +59,8 @@
     CurSection->addPendingLabel(S, CurSubsectionIdx);
 
     // Add this Section to the list of PendingLabelSections.
-    auto SecIt = std::find(PendingLabelSections.begin(),
-                           PendingLabelSections.end(), CurSection);
-    if (SecIt == PendingLabelSections.end())
-      PendingLabelSections.push_back(CurSection);
-  }
-  else
+    PendingLabelSections.insert(CurSection);
+  } else
     // There is no Section / Subsection for this label yet.
     PendingLabels.push_back(S);
 }