diff --git a/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp b/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp
index cfdfd94b4e27a..5066a99fa0858 100644
--- a/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp
+++ b/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp
@@ -1033,19 +1033,17 @@ class IndexCallsiteContextGraph
 };
 } // namespace
 
-namespace llvm {
 template <>
-struct DenseMapInfo<typename CallsiteContextGraph<
+struct llvm::DenseMapInfo<typename CallsiteContextGraph<
     ModuleCallsiteContextGraph, Function, Instruction *>::CallInfo>
     : public DenseMapInfo<std::pair<Instruction *, unsigned>> {};
 template <>
-struct DenseMapInfo<typename CallsiteContextGraph<
+struct llvm::DenseMapInfo<typename CallsiteContextGraph<
     IndexCallsiteContextGraph, FunctionSummary, IndexCall>::CallInfo>
     : public DenseMapInfo<std::pair<IndexCall, unsigned>> {};
 template <>
-struct DenseMapInfo<IndexCall>
+struct llvm::DenseMapInfo<IndexCall>
     : public DenseMapInfo<PointerUnion<CallsiteInfo *, AllocInfo *>> {};
-} // end namespace llvm
 
 namespace {
 
diff --git a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
index ac41fdd988605..2d5cb8268ffdd 100644
--- a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -372,9 +372,7 @@ struct VTableSlot {
 
 } // end anonymous namespace
 
-namespace llvm {
-
-template <> struct DenseMapInfo<VTableSlot> {
+template <> struct llvm::DenseMapInfo<VTableSlot> {
   static VTableSlot getEmptyKey() {
     return {DenseMapInfo<Metadata *>::getEmptyKey(),
             DenseMapInfo<uint64_t>::getEmptyKey()};
@@ -393,7 +391,7 @@ template <> struct DenseMapInfo<VTableSlot> {
   }
 };
 
-template <> struct DenseMapInfo<VTableSlotSummary> {
+template <> struct llvm::DenseMapInfo<VTableSlotSummary> {
   static VTableSlotSummary getEmptyKey() {
     return {DenseMapInfo<StringRef>::getEmptyKey(),
             DenseMapInfo<uint64_t>::getEmptyKey()};
@@ -412,8 +410,6 @@ template <> struct DenseMapInfo<VTableSlotSummary> {
   }
 };
 
-} // end namespace llvm
-
 // Returns true if the function must be unreachable based on ValueInfo.
 //
 // In particular, identifies a function as unreachable in the following
diff --git a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
index 5c747bbaa53af..9815644f5f43d 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -1069,27 +1069,22 @@ struct LoweredPHIRecord {
 };
 } // namespace
 
-namespace llvm {
-  template<>
-  struct DenseMapInfo<LoweredPHIRecord> {
-    static inline LoweredPHIRecord getEmptyKey() {
-      return LoweredPHIRecord(nullptr, 0);
-    }
-    static inline LoweredPHIRecord getTombstoneKey() {
-      return LoweredPHIRecord(nullptr, 1);
-    }
-    static unsigned getHashValue(const LoweredPHIRecord &Val) {
-      return DenseMapInfo<PHINode*>::getHashValue(Val.PN) ^ (Val.Shift>>3) ^
-             (Val.Width>>3);
-    }
-    static bool isEqual(const LoweredPHIRecord &LHS,
-                        const LoweredPHIRecord &RHS) {
-      return LHS.PN == RHS.PN && LHS.Shift == RHS.Shift &&
-             LHS.Width == RHS.Width;
-    }
-  };
-} // namespace llvm
-
+template <> struct llvm::DenseMapInfo<LoweredPHIRecord> {
+  static inline LoweredPHIRecord getEmptyKey() {
+    return LoweredPHIRecord(nullptr, 0);
+  }
+  static inline LoweredPHIRecord getTombstoneKey() {
+    return LoweredPHIRecord(nullptr, 1);
+  }
+  static unsigned getHashValue(const LoweredPHIRecord &Val) {
+    return DenseMapInfo<PHINode *>::getHashValue(Val.PN) ^ (Val.Shift >> 3) ^
+           (Val.Width >> 3);
+  }
+  static bool isEqual(const LoweredPHIRecord &LHS,
+                      const LoweredPHIRecord &RHS) {
+    return LHS.PN == RHS.PN && LHS.Shift == RHS.Shift && LHS.Width == RHS.Width;
+  }
+};
 
 /// This is an integer PHI and we know that it has an illegal type: see if it is
 /// only used by trunc or trunc(lshr) operations. If so, we split the PHI into
diff --git a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
index 0f8cc6ca6ed21..2afa7b7d40386 100644
--- a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
+++ b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
@@ -108,7 +108,7 @@ struct SimpleValue {
     // of instruction handled below (UnaryOperator, etc.).
     if (CallInst *CI = dyn_cast<CallInst>(Inst)) {
       if (Function *F = CI->getCalledFunction()) {
-        switch ((Intrinsic::ID)F->getIntrinsicID()) {
+        switch (F->getIntrinsicID()) {
         case Intrinsic::experimental_constrained_fadd:
         case Intrinsic::experimental_constrained_fsub:
         case Intrinsic::experimental_constrained_fmul:
@@ -154,9 +154,7 @@ struct SimpleValue {
 
 } // end anonymous namespace
 
-namespace llvm {
-
-template <> struct DenseMapInfo<SimpleValue> {
+template <> struct llvm::DenseMapInfo<SimpleValue> {
   static inline SimpleValue getEmptyKey() {
     return DenseMapInfo<Instruction *>::getEmptyKey();
   }
@@ -169,8 +167,6 @@ template <> struct DenseMapInfo<SimpleValue> {
   static bool isEqual(SimpleValue LHS, SimpleValue RHS);
 };
 
-} // end namespace llvm
-
 /// Match a 'select' including an optional 'not's of the condition.
 static bool matchSelectWithOptionalNotCond(Value *V, Value *&Cond, Value *&A,
                                            Value *&B,
@@ -509,9 +505,7 @@ struct CallValue {
 
 } // end anonymous namespace
 
-namespace llvm {
-
-template <> struct DenseMapInfo<CallValue> {
+template <> struct llvm::DenseMapInfo<CallValue> {
   static inline CallValue getEmptyKey() {
     return DenseMapInfo<Instruction *>::getEmptyKey();
   }
@@ -524,8 +518,6 @@ template <> struct DenseMapInfo<CallValue> {
   static bool isEqual(CallValue LHS, CallValue RHS);
 };
 
-} // end namespace llvm
-
 unsigned DenseMapInfo<CallValue>::getHashValue(CallValue Val) {
   Instruction *Inst = Val.Inst;
 
@@ -580,9 +572,7 @@ struct GEPValue {
 
 } // namespace
 
-namespace llvm {
-
-template <> struct DenseMapInfo<GEPValue> {
+template <> struct llvm::DenseMapInfo<GEPValue> {
   static inline GEPValue getEmptyKey() {
     return DenseMapInfo<Instruction *>::getEmptyKey();
   }
@@ -595,8 +585,6 @@ template <> struct DenseMapInfo<GEPValue> {
   static bool isEqual(const GEPValue &LHS, const GEPValue &RHS);
 };
 
-} // end namespace llvm
-
 unsigned DenseMapInfo<GEPValue>::getHashValue(const GEPValue &Val) {
   auto *GEP = cast<GetElementPtrInst>(Val.Inst);
   if (Val.ConstantOffset.has_value())
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 638952a3aa58f..ee53594900bb3 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -170,9 +170,7 @@ struct llvm::GVNPass::Expression {
   }
 };
 
-namespace llvm {
-
-template <> struct DenseMapInfo<GVNPass::Expression> {
+template <> struct llvm::DenseMapInfo<GVNPass::Expression> {
   static inline GVNPass::Expression getEmptyKey() { return ~0U; }
   static inline GVNPass::Expression getTombstoneKey() { return ~1U; }
 
@@ -188,8 +186,6 @@ template <> struct DenseMapInfo<GVNPass::Expression> {
   }
 };
 
-} // end namespace llvm
-
 /// Represents a particular available value that we know how to materialize.
 /// Materialization of an AvailableValue never fails.  An AvailableValue is
 /// implicitly associated with a rematerialization point which is the
diff --git a/llvm/lib/Transforms/Scalar/NewGVN.cpp b/llvm/lib/Transforms/Scalar/NewGVN.cpp
index 3c1a8ba308bf9..80aa98d59d3c6 100644
--- a/llvm/lib/Transforms/Scalar/NewGVN.cpp
+++ b/llvm/lib/Transforms/Scalar/NewGVN.cpp
@@ -434,10 +434,6 @@ class CongruenceClass {
   int StoreCount = 0;
 };
 
-} // end anonymous namespace
-
-namespace llvm {
-
 struct ExactEqualsExpression {
   const Expression &E;
 
@@ -449,8 +445,9 @@ struct ExactEqualsExpression {
     return E.exactlyEquals(Other);
   }
 };
+} // end anonymous namespace
 
-template <> struct DenseMapInfo<const Expression *> {
+template <> struct llvm::DenseMapInfo<const Expression *> {
   static const Expression *getEmptyKey() {
     auto Val = static_cast<uintptr_t>(-1);
     Val <<= PointerLikeTypeTraits<const Expression *>::NumLowBitsAvailable;
@@ -493,8 +490,6 @@ template <> struct DenseMapInfo<const Expression *> {
   }
 };
 
-} // end namespace llvm
-
 namespace {
 
 class NewGVN {
diff --git a/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp b/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp
index 2190dcdc8aeaa..a87822c0ac1d7 100644
--- a/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp
+++ b/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp
@@ -84,10 +84,6 @@ class CanonicalizeFreezeInLoopsImpl {
   bool run();
 };
 
-} // anonymous namespace
-
-namespace llvm {
-
 struct FrozenIndPHIInfo {
   // A freeze instruction that uses an induction phi
   FreezeInst *FI = nullptr;
@@ -103,7 +99,9 @@ struct FrozenIndPHIInfo {
   bool operator==(const FrozenIndPHIInfo &Other) { return FI == Other.FI; }
 };
 
-template <> struct DenseMapInfo<FrozenIndPHIInfo> {
+} // namespace
+
+template <> struct llvm::DenseMapInfo<FrozenIndPHIInfo> {
   static inline FrozenIndPHIInfo getEmptyKey() {
     return FrozenIndPHIInfo(DenseMapInfo<PHINode *>::getEmptyKey(),
                             DenseMapInfo<BinaryOperator *>::getEmptyKey());
@@ -124,8 +122,6 @@ template <> struct DenseMapInfo<FrozenIndPHIInfo> {
   };
 };
 
-} // end namespace llvm
-
 // Given U = (value, user), replace value with freeze(value), and let
 // SCEV forget user. The inserted freeze is placed in the preheader.
 void CanonicalizeFreezeInLoopsImpl::InsertFreezeAndForgetFromSCEV(Use &U) {
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 155fcc50bdebf..fb1551671f362 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -7736,8 +7736,7 @@ struct SwitchSuccWrapper {
   DenseMap<PHINode *, SmallDenseMap<BasicBlock *, Value *, 8>> *PhiPredIVs;
 };
 
-namespace llvm {
-template <> struct DenseMapInfo<const SwitchSuccWrapper *> {
+template <> struct llvm::DenseMapInfo<const SwitchSuccWrapper *> {
   static const SwitchSuccWrapper *getEmptyKey() {
     return static_cast<SwitchSuccWrapper *>(
         DenseMapInfo<void *>::getEmptyKey());
@@ -7805,7 +7804,6 @@ template <> struct DenseMapInfo<const SwitchSuccWrapper *> {
     return true;
   }
 };
-} // namespace llvm
 
 bool SimplifyCFGOpt::simplifyDuplicateSwitchArms(SwitchInst *SI,
                                                  DomTreeUpdater *DTU) {