diff --git a/llvm/include/llvm/ADT/GenericCycleImpl.h b/llvm/include/llvm/ADT/GenericCycleImpl.h
--- a/llvm/include/llvm/ADT/GenericCycleImpl.h
+++ b/llvm/include/llvm/ADT/GenericCycleImpl.h
@@ -177,8 +177,7 @@
   CurrentContainer.pop_back();
   Child->ParentCycle = NewParent;
 
-  NewParent->Blocks.insert(NewParent->Blocks.end(), Child->block_begin(),
-                           Child->block_end());
+  NewParent->Blocks.insert(Child->block_begin(), Child->block_end());
 
   for (auto &It : BlockMapTopLevel)
     if (It.second == Child)
@@ -266,7 +265,7 @@
       } else {
         Info.BlockMap.try_emplace(Block, NewCycle.get());
         assert(!is_contained(NewCycle->Blocks, Block));
-        NewCycle->Blocks.push_back(Block);
+        NewCycle->Blocks.insert(Block);
         ProcessPredecessors(Block);
         Info.BlockMapTopLevel.try_emplace(Block, NewCycle.get());
       }
diff --git a/llvm/include/llvm/ADT/GenericCycleInfo.h b/llvm/include/llvm/ADT/GenericCycleInfo.h
--- a/llvm/include/llvm/ADT/GenericCycleInfo.h
+++ b/llvm/include/llvm/ADT/GenericCycleInfo.h
@@ -32,6 +32,8 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/GenericSSAContext.h"
 #include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/iterator.h"
 #include "llvm/Support/Debug.h"
@@ -67,7 +69,9 @@
 
   /// Basic blocks that are contained in the cycle, including entry blocks,
   /// and including blocks that are part of a child cycle.
-  std::vector<BlockT *> Blocks;
+  using BlockSetVectorT = SetVector<BlockT *, std::vector<BlockT *>,
+                                    SmallPtrSet<const BlockT *, 8>>;
+  BlockSetVectorT Blocks;
 
   /// Depth of the cycle in the tree. The root "cycle" is at depth 0.
   ///
@@ -85,7 +89,7 @@
   }
 
   void appendEntry(BlockT *Block) { Entries.push_back(Block); }
-  void appendBlock(BlockT *Block) { Blocks.push_back(Block); }
+  void appendBlock(BlockT *Block) { Blocks.insert(Block); }
 
   GenericCycle(const GenericCycle &) = delete;
   GenericCycle &operator=(const GenericCycle &) = delete;
@@ -110,9 +114,7 @@
   }
 
   /// \brief Return whether \p Block is contained in the cycle.
-  bool contains(const BlockT *Block) const {
-    return is_contained(Blocks, Block);
-  }
+  bool contains(const BlockT *Block) const { return Blocks.contains(Block); }
 
   /// \brief Returns true iff this cycle contains \p C.
   ///
@@ -171,7 +173,7 @@
 
   /// Iteration over blocks in the cycle (including entry blocks).
   //@{
-  using const_block_iterator = typename std::vector<BlockT *>::const_iterator;
+  using const_block_iterator = typename BlockSetVectorT::const_iterator;
 
   const_block_iterator block_begin() const {
     return const_block_iterator{Blocks.begin()};
diff --git a/llvm/include/llvm/ADT/SetVector.h b/llvm/include/llvm/ADT/SetVector.h
--- a/llvm/include/llvm/ADT/SetVector.h
+++ b/llvm/include/llvm/ADT/SetVector.h
@@ -39,10 +39,10 @@
           typename Set = DenseSet<T>>
 class SetVector {
 public:
-  using value_type = T;
-  using key_type = T;
-  using reference = T&;
-  using const_reference = const T&;
+  using value_type = typename Vector::value_type;
+  using key_type = typename Set::key_type;
+  using reference = value_type &;
+  using const_reference = const value_type &;
   using set_type = Set;
   using vector_type = Vector;
   using iterator = typename vector_type::const_iterator;
@@ -60,7 +60,7 @@
     insert(Start, End);
   }
 
-  ArrayRef<T> getArrayRef() const { return vector_; }
+  ArrayRef<value_type> getArrayRef() const { return vector_; }
 
   /// Clear the SetVector and return the underlying vector.
   Vector takeVector() {
@@ -119,13 +119,13 @@
   }
 
   /// Return the first element of the SetVector.
-  const T &front() const {
+  const value_type &front() const {
     assert(!empty() && "Cannot call front() on empty SetVector!");
     return vector_.front();
   }
 
   /// Return the last element of the SetVector.
-  const T &back() const {
+  const value_type &back() const {
     assert(!empty() && "Cannot call back() on empty SetVector!");
     return vector_.back();
   }
@@ -222,8 +222,8 @@
     vector_.pop_back();
   }
 
-  [[nodiscard]] T pop_back_val() {
-    T Ret = back();
+  [[nodiscard]] value_type pop_back_val() {
+    value_type Ret = back();
     pop_back();
     return Ret;
   }
diff --git a/llvm/include/llvm/ADT/SmallSet.h b/llvm/include/llvm/ADT/SmallSet.h
--- a/llvm/include/llvm/ADT/SmallSet.h
+++ b/llvm/include/llvm/ADT/SmallSet.h
@@ -149,7 +149,9 @@
   static_assert(N <= 32, "N should be small");
 
 public:
+  using key_type = T;
   using size_type = size_t;
+  using value_type = T;
   using const_iterator = SmallSetIterator<T, N, C>;
 
   SmallSet() = default;