diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 95d954f6b8174..0c8565c927a24 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -758,14 +758,12 @@ void TypePrinting::printStructBody(StructType *STy, raw_ostream &OS) {
 
 AbstractSlotTrackerStorage::~AbstractSlotTrackerStorage() = default;
 
-namespace llvm {
-
 //===----------------------------------------------------------------------===//
 // SlotTracker Class: Enumerate slot numbers for unnamed values
 //===----------------------------------------------------------------------===//
 /// This class provides computation of slot numbers for LLVM Assembly writing.
 ///
-class SlotTracker : public AbstractSlotTrackerStorage {
+class llvm::SlotTracker : public AbstractSlotTrackerStorage {
 public:
   /// ValueMap - A mapping of Values to slot numbers.
   using ValueMap = DenseMap<const Value *, unsigned>;
@@ -943,8 +941,6 @@ class SlotTracker : public AbstractSlotTrackerStorage {
   void processDbgRecordMetadata(const DbgRecord &DVR);
 };
 
-} // end namespace llvm
-
 ModuleSlotTracker::ModuleSlotTracker(SlotTracker &Machine, const Module *M,
                                      const Function *F)
     : M(M), F(F), Machine(&Machine) {}
diff --git a/llvm/lib/IR/DebugLoc.cpp b/llvm/lib/IR/DebugLoc.cpp
index 01dafcab94ce9..bfba6e0cab6bf 100644
--- a/llvm/lib/IR/DebugLoc.cpp
+++ b/llvm/lib/IR/DebugLoc.cpp
@@ -10,10 +10,11 @@
 #include "llvm/Config/llvm-config.h"
 #include "llvm/IR/DebugInfo.h"
 
+using namespace llvm;
+
 #if LLVM_ENABLE_DEBUGLOC_TRACKING_ORIGIN
 #include "llvm/Support/Signals.h"
 
-namespace llvm {
 DbgLocOrigin::DbgLocOrigin(bool ShouldCollectTrace) {
   if (!ShouldCollectTrace)
     return;
@@ -30,11 +31,8 @@ void DbgLocOrigin::addTrace() {
   auto &[Depth, StackTrace] = StackTraces.emplace_back();
   Depth = sys::getStackTrace(StackTrace);
 }
-} // namespace llvm
 #endif
 
-using namespace llvm;
-
 #if LLVM_ENABLE_DEBUGLOC_TRACKING_COVERAGE
 DILocAndCoverageTracking::DILocAndCoverageTracking(const DILocation *L)
     : TrackingMDNodeRef(const_cast<DILocation *>(L)), DbgLocOrigin(!L),
diff --git a/llvm/lib/IR/DebugProgramInstruction.cpp b/llvm/lib/IR/DebugProgramInstruction.cpp
index d9357bba75510..6b1fd3907dc41 100644
--- a/llvm/lib/IR/DebugProgramInstruction.cpp
+++ b/llvm/lib/IR/DebugProgramInstruction.cpp
@@ -12,8 +12,9 @@
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/Support/Compiler.h"
 
-namespace llvm {
+using namespace llvm;
 
+namespace llvm {
 template <typename T>
 DbgRecordParamRef<T>::DbgRecordParamRef(const T *Param)
     : Ref(const_cast<T *>(Param)) {}
@@ -28,6 +29,7 @@ template <typename T> T *DbgRecordParamRef<T>::get() const {
 template class LLVM_EXPORT_TEMPLATE DbgRecordParamRef<DIExpression>;
 template class LLVM_EXPORT_TEMPLATE DbgRecordParamRef<DILabel>;
 template class LLVM_EXPORT_TEMPLATE DbgRecordParamRef<DILocalVariable>;
+} // namespace llvm
 
 DbgVariableRecord::DbgVariableRecord(const DbgVariableIntrinsic *DVI)
     : DbgRecord(ValueKind, DVI->getDebugLoc()),
@@ -755,5 +757,3 @@ iterator_range<simple_ilist<DbgRecord>::iterator> DbgMarker::cloneDebugInfoFrom(
     // We inserted a block at the end, return that range.
     return {First->getIterator(), StoredDbgRecords.end()};
 }
-
-} // end namespace llvm
diff --git a/llvm/lib/IR/FPEnv.cpp b/llvm/lib/IR/FPEnv.cpp
index 67f21d3756e93..c41d7b3181a37 100644
--- a/llvm/lib/IR/FPEnv.cpp
+++ b/llvm/lib/IR/FPEnv.cpp
@@ -19,9 +19,10 @@
 #include "llvm/IR/Intrinsics.h"
 #include <optional>
 
-namespace llvm {
+using namespace llvm;
 
-std::optional<RoundingMode> convertStrToRoundingMode(StringRef RoundingArg) {
+std::optional<RoundingMode>
+llvm::convertStrToRoundingMode(StringRef RoundingArg) {
   // For dynamic rounding mode, we use round to nearest but we will set the
   // 'exact' SDNodeFlag so that the value will not be rounded.
   return StringSwitch<std::optional<RoundingMode>>(RoundingArg)
@@ -34,7 +35,8 @@ std::optional<RoundingMode> convertStrToRoundingMode(StringRef RoundingArg) {
       .Default(std::nullopt);
 }
 
-std::optional<StringRef> convertRoundingModeToStr(RoundingMode UseRounding) {
+std::optional<StringRef>
+llvm::convertRoundingModeToStr(RoundingMode UseRounding) {
   std::optional<StringRef> RoundingStr;
   switch (UseRounding) {
   case RoundingMode::Dynamic:
@@ -62,7 +64,7 @@ std::optional<StringRef> convertRoundingModeToStr(RoundingMode UseRounding) {
 }
 
 std::optional<fp::ExceptionBehavior>
-convertStrToExceptionBehavior(StringRef ExceptionArg) {
+llvm::convertStrToExceptionBehavior(StringRef ExceptionArg) {
   return StringSwitch<std::optional<fp::ExceptionBehavior>>(ExceptionArg)
       .Case("fpexcept.ignore", fp::ebIgnore)
       .Case("fpexcept.maytrap", fp::ebMayTrap)
@@ -71,7 +73,7 @@ convertStrToExceptionBehavior(StringRef ExceptionArg) {
 }
 
 std::optional<StringRef>
-convertExceptionBehaviorToStr(fp::ExceptionBehavior UseExcept) {
+llvm::convertExceptionBehaviorToStr(fp::ExceptionBehavior UseExcept) {
   std::optional<StringRef> ExceptStr;
   switch (UseExcept) {
   case fp::ebStrict:
@@ -87,7 +89,7 @@ convertExceptionBehaviorToStr(fp::ExceptionBehavior UseExcept) {
   return ExceptStr;
 }
 
-Intrinsic::ID getConstrainedIntrinsicID(const Instruction &Instr) {
+Intrinsic::ID llvm::getConstrainedIntrinsicID(const Instruction &Instr) {
   Intrinsic::ID IID = Intrinsic::not_intrinsic;
   switch (Instr.getOpcode()) {
   case Instruction::FCmp:
@@ -127,5 +129,3 @@ Intrinsic::ID getConstrainedIntrinsicID(const Instruction &Instr) {
 
   return IID;
 }
-
-} // namespace llvm
diff --git a/llvm/lib/IR/Operator.cpp b/llvm/lib/IR/Operator.cpp
index 39e5463cb6fc3..c3e54a0fc0c7e 100644
--- a/llvm/lib/IR/Operator.cpp
+++ b/llvm/lib/IR/Operator.cpp
@@ -17,7 +17,8 @@
 
 #include "ConstantsContext.h"
 
-namespace llvm {
+using namespace llvm;
+
 bool Operator::hasPoisonGeneratingFlags() const {
   switch (getOpcode()) {
   case Instruction::Add:
@@ -288,4 +289,3 @@ void FastMathFlags::print(raw_ostream &O) const {
       O << " afn";
   }
 }
-} // namespace llvm
diff --git a/llvm/lib/IR/PassTimingInfo.cpp b/llvm/lib/IR/PassTimingInfo.cpp
index 4e27086e97ac5..cb1b91a98b036 100644
--- a/llvm/lib/IR/PassTimingInfo.cpp
+++ b/llvm/lib/IR/PassTimingInfo.cpp
@@ -32,10 +32,10 @@ using namespace llvm;
 
 #define DEBUG_TYPE "time-passes"
 
-namespace llvm {
+using namespace llvm;
 
-bool TimePassesIsEnabled = false;
-bool TimePassesPerRun = false;
+bool llvm::TimePassesIsEnabled = false;
+bool llvm::TimePassesPerRun = false;
 
 static cl::opt<bool, true> EnableTiming(
     "time-passes", cl::location(TimePassesIsEnabled), cl::Hidden,
@@ -139,7 +139,7 @@ PassTimingInfo *PassTimingInfo::TheTimeInfo;
 } // namespace legacy
 } // namespace
 
-Timer *getPassTimer(Pass *P) {
+Timer *llvm::getPassTimer(Pass *P) {
   legacy::PassTimingInfo::init();
   if (legacy::PassTimingInfo::TheTimeInfo)
     return legacy::PassTimingInfo::TheTimeInfo->getPassTimer(P, P);
@@ -148,7 +148,7 @@ Timer *getPassTimer(Pass *P) {
 
 /// If timing is enabled, report the times collected up to now and then reset
 /// them.
-void reportAndResetTimings(raw_ostream *OutStream) {
+void llvm::reportAndResetTimings(raw_ostream *OutStream) {
   if (legacy::PassTimingInfo::TheTimeInfo)
     legacy::PassTimingInfo::TheTimeInfo->print(OutStream);
 }
@@ -315,5 +315,3 @@ void TimePassesHandler::registerCallbacks(PassInstrumentationCallbacks &PIC) {
   PIC.registerAfterAnalysisCallback(
       [this](StringRef P, Any) { this->stopAnalysisTimer(P); });
 }
-
-} // namespace llvm
diff --git a/llvm/lib/IR/PseudoProbe.cpp b/llvm/lib/IR/PseudoProbe.cpp
index 59f218cc3683b..3c05f4b1f86a2 100644
--- a/llvm/lib/IR/PseudoProbe.cpp
+++ b/llvm/lib/IR/PseudoProbe.cpp
@@ -19,9 +19,7 @@
 
 using namespace llvm;
 
-namespace llvm {
-
-std::optional<PseudoProbe>
+static std::optional<PseudoProbe>
 extractProbeFromDiscriminator(const DILocation *DIL) {
   if (DIL) {
     auto Discriminator = DIL->getDiscriminator();
@@ -43,7 +41,7 @@ extractProbeFromDiscriminator(const DILocation *DIL) {
   return std::nullopt;
 }
 
-std::optional<PseudoProbe>
+static std::optional<PseudoProbe>
 extractProbeFromDiscriminator(const Instruction &Inst) {
   assert(isa<CallBase>(&Inst) && !isa<IntrinsicInst>(&Inst) &&
          "Only call instructions should have pseudo probe encodes as their "
@@ -53,7 +51,7 @@ extractProbeFromDiscriminator(const Instruction &Inst) {
   return std::nullopt;
 }
 
-std::optional<PseudoProbe> extractProbe(const Instruction &Inst) {
+std::optional<PseudoProbe> llvm::extractProbe(const Instruction &Inst) {
   if (const auto *II = dyn_cast<PseudoProbeInst>(&Inst)) {
     PseudoProbe Probe;
     Probe.Id = II->getIndex()->getZExtValue();
@@ -73,7 +71,7 @@ std::optional<PseudoProbe> extractProbe(const Instruction &Inst) {
   return std::nullopt;
 }
 
-void setProbeDistributionFactor(Instruction &Inst, float Factor) {
+void llvm::setProbeDistributionFactor(Instruction &Inst, float Factor) {
   assert(Factor >= 0 && Factor <= 1 &&
          "Distribution factor must be in [0, 1.0]");
   if (auto *II = dyn_cast<PseudoProbeInst>(&Inst)) {
@@ -111,5 +109,3 @@ void setProbeDistributionFactor(Instruction &Inst, float Factor) {
     }
   }
 }
-
-} // namespace llvm
diff --git a/llvm/lib/IR/ReplaceConstant.cpp b/llvm/lib/IR/ReplaceConstant.cpp
index 962368f061851..b3586b45a23f2 100644
--- a/llvm/lib/IR/ReplaceConstant.cpp
+++ b/llvm/lib/IR/ReplaceConstant.cpp
@@ -16,7 +16,7 @@
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Instructions.h"
 
-namespace llvm {
+using namespace llvm;
 
 static bool isExpandableUser(User *U) {
   return isa<ConstantExpr>(U) || isa<ConstantAggregate>(U);
@@ -49,10 +49,10 @@ static SmallVector<Instruction *, 4> expandUser(BasicBlock::iterator InsertPt,
   return NewInsts;
 }
 
-bool convertUsersOfConstantsToInstructions(ArrayRef<Constant *> Consts,
-                                           Function *RestrictToFunc,
-                                           bool RemoveDeadConstants,
-                                           bool IncludeSelf) {
+bool llvm::convertUsersOfConstantsToInstructions(ArrayRef<Constant *> Consts,
+                                                 Function *RestrictToFunc,
+                                                 bool RemoveDeadConstants,
+                                                 bool IncludeSelf) {
   // Find all expandable direct users of Consts.
   SmallVector<Constant *> Stack;
   for (Constant *C : Consts) {
@@ -121,5 +121,3 @@ bool convertUsersOfConstantsToInstructions(ArrayRef<Constant *> Consts,
 
   return Changed;
 }
-
-} // namespace llvm
diff --git a/llvm/lib/IR/Use.cpp b/llvm/lib/IR/Use.cpp
index 67882ba0144b4..504233575594d 100644
--- a/llvm/lib/IR/Use.cpp
+++ b/llvm/lib/IR/Use.cpp
@@ -9,7 +9,7 @@
 #include "llvm/IR/Use.h"
 #include "llvm/IR/User.h"
 
-namespace llvm {
+using namespace llvm;
 
 void Use::swap(Use &RHS) {
   if (Val == RHS.Val)
@@ -42,5 +42,3 @@ void Use::zap(Use *Start, const Use *Stop, bool del) {
   if (del)
     ::operator delete(Start);
 }
-
-} // namespace llvm
diff --git a/llvm/lib/IR/User.cpp b/llvm/lib/IR/User.cpp
index ab44cb4b8a3f7..9bb7c1298593a 100644
--- a/llvm/lib/IR/User.cpp
+++ b/llvm/lib/IR/User.cpp
@@ -11,8 +11,11 @@
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/IntrinsicInst.h"
 
+using namespace llvm;
+
 namespace llvm {
 class BasicBlock;
+}
 
 //===----------------------------------------------------------------------===//
 //                                 User Class
@@ -214,5 +217,3 @@ LLVM_NO_SANITIZE_MEMORY_ATTRIBUTE void User::operator delete(void *Usr) {
     ::operator delete(Storage);
   }
 }
-
-} // namespace llvm
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 7917712846990..24f90bf6de7f5 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -136,9 +136,7 @@ static cl::opt<bool> VerifyNoAliasScopeDomination(
     cl::desc("Ensure that llvm.experimental.noalias.scope.decl for identical "
              "scopes are not dominating"));
 
-namespace llvm {
-
-struct VerifierSupport {
+struct llvm::VerifierSupport {
   raw_ostream *OS;
   const Module &M;
   ModuleSlotTracker MST;
@@ -318,8 +316,6 @@ struct VerifierSupport {
   }
 };
 
-} // namespace llvm
-
 namespace {
 
 class Verifier : public InstVisitor<Verifier>, VerifierSupport {