diff --git a/llvm/tools/llvm-profgen/CSPreInliner.h b/llvm/tools/llvm-profgen/CSPreInliner.h
index 8a3f16a4f13cb..022c3f8d0daed 100644
--- a/llvm/tools/llvm-profgen/CSPreInliner.h
+++ b/llvm/tools/llvm-profgen/CSPreInliner.h
@@ -16,9 +16,6 @@
 #include "llvm/Transforms/IPO/ProfiledCallGraph.h"
 #include "llvm/Transforms/IPO/SampleContextTracker.h"
 
-using namespace llvm;
-using namespace sampleprof;
-
 namespace llvm {
 namespace sampleprof {
 
diff --git a/llvm/tools/llvm-profgen/ErrorHandling.h b/llvm/tools/llvm-profgen/ErrorHandling.h
index b797add8a892f..17084bd785e64 100644
--- a/llvm/tools/llvm-profgen/ErrorHandling.h
+++ b/llvm/tools/llvm-profgen/ErrorHandling.h
@@ -16,7 +16,7 @@
 #include "llvm/Support/WithColor.h"
 #include <system_error>
 
-using namespace llvm;
+namespace llvm {
 
 [[noreturn]] inline void exitWithError(const Twine &Message,
                                        StringRef Whence = StringRef(),
@@ -53,4 +53,6 @@ inline void emitWarningSummary(uint64_t Num, uint64_t Total, StringRef Msg) {
                        << "%(" << Num << "/" << Total << ") " << Msg << "\n";
 }
 
+} // end namespace llvm
+
 #endif
diff --git a/llvm/tools/llvm-profgen/PerfReader.cpp b/llvm/tools/llvm-profgen/PerfReader.cpp
index ad113eda27914..4ab5f2e63fd12 100644
--- a/llvm/tools/llvm-profgen/PerfReader.cpp
+++ b/llvm/tools/llvm-profgen/PerfReader.cpp
@@ -15,6 +15,8 @@
 
 #define DEBUG_TYPE "perf-reader"
 
+using namespace llvm;
+
 cl::opt<bool> SkipSymbolization("skip-symbolization",
                                 cl::desc("Dump the unsymbolized profile to the "
                                          "output file. It will show unwinder "
@@ -47,9 +49,6 @@ static cl::opt<int> CSProfMaxUnsymbolizedCtxDepth(
     cl::desc("Keep the last K contexts while merging unsymbolized profile. -1 "
              "means no depth limit."));
 
-extern cl::opt<std::string> PerfTraceFilename;
-extern cl::opt<bool> ShowDisassemblyOnly;
-extern cl::opt<bool> ShowSourceLocations;
 extern cl::opt<std::string> OutputFilename;
 
 namespace llvm {
diff --git a/llvm/tools/llvm-profgen/PerfReader.h b/llvm/tools/llvm-profgen/PerfReader.h
index 4b3ac8f569755..19451915812e1 100644
--- a/llvm/tools/llvm-profgen/PerfReader.h
+++ b/llvm/tools/llvm-profgen/PerfReader.h
@@ -17,9 +17,6 @@
 #include <fstream>
 #include <map>
 
-using namespace llvm;
-using namespace sampleprof;
-
 namespace llvm {
 
 class CleanupInstaller;
diff --git a/llvm/tools/llvm-profgen/ProfileGenerator.cpp b/llvm/tools/llvm-profgen/ProfileGenerator.cpp
index db686c3b597eb..9468228acc427 100644
--- a/llvm/tools/llvm-profgen/ProfileGenerator.cpp
+++ b/llvm/tools/llvm-profgen/ProfileGenerator.cpp
@@ -17,6 +17,9 @@
 #include <unordered_set>
 #include <utility>
 
+using namespace llvm;
+using namespace sampleprof;
+
 cl::opt<std::string> OutputFilename("output", cl::value_desc("output"),
                                     cl::Required,
                                     cl::desc("Output profile file"));
@@ -104,9 +107,6 @@ cl::opt<bool> InferMissingFrames(
         "Infer missing call frames due to compiler tail call elimination."),
     llvm::cl::Optional);
 
-using namespace llvm;
-using namespace sampleprof;
-
 namespace llvm {
 
 namespace sampleprof {
diff --git a/llvm/tools/llvm-profgen/ProfileGenerator.h b/llvm/tools/llvm-profgen/ProfileGenerator.h
index 5e36128530cd9..d3e04563a81c2 100644
--- a/llvm/tools/llvm-profgen/ProfileGenerator.h
+++ b/llvm/tools/llvm-profgen/ProfileGenerator.h
@@ -17,9 +17,6 @@
 #include <memory>
 #include <unordered_set>
 
-using namespace llvm;
-using namespace sampleprof;
-
 namespace llvm {
 namespace sampleprof {
 
diff --git a/llvm/tools/llvm-profgen/ProfiledBinary.cpp b/llvm/tools/llvm-profgen/ProfiledBinary.cpp
index 6847ba1b21b1f..beef4338d5f89 100644
--- a/llvm/tools/llvm-profgen/ProfiledBinary.cpp
+++ b/llvm/tools/llvm-profgen/ProfiledBinary.cpp
@@ -25,6 +25,7 @@
 #define DEBUG_TYPE "load-binary"
 
 using namespace llvm;
+using namespace llvm::object;
 using namespace sampleprof;
 
 cl::opt<bool> ShowDisassemblyOnly("show-disassembly-only",
diff --git a/llvm/tools/llvm-profgen/ProfiledBinary.h b/llvm/tools/llvm-profgen/ProfiledBinary.h
index 0588cb48b2af6..fd2fa5301d31d 100644
--- a/llvm/tools/llvm-profgen/ProfiledBinary.h
+++ b/llvm/tools/llvm-profgen/ProfiledBinary.h
@@ -42,15 +42,10 @@
 #include <vector>
 
 namespace llvm {
+
 extern cl::opt<bool> EnableCSPreInliner;
 extern cl::opt<bool> UseContextCostForPreInliner;
-} // namespace llvm
-
-using namespace llvm;
-using namespace sampleprof;
-using namespace llvm::object;
 
-namespace llvm {
 namespace sampleprof {
 
 class ProfiledBinary;
@@ -303,34 +298,34 @@ class ProfiledBinary {
 
   bool IsCOFF = false;
 
-  void setPreferredTextSegmentAddresses(const ObjectFile *O);
+  void setPreferredTextSegmentAddresses(const object::ObjectFile *O);
 
   template <class ELFT>
-  void setPreferredTextSegmentAddresses(const ELFFile<ELFT> &Obj,
+  void setPreferredTextSegmentAddresses(const object::ELFFile<ELFT> &Obj,
                                         StringRef FileName);
-  void setPreferredTextSegmentAddresses(const COFFObjectFile *Obj,
+  void setPreferredTextSegmentAddresses(const object::COFFObjectFile *Obj,
                                         StringRef FileName);
 
-  void checkPseudoProbe(const ELFObjectFileBase *Obj);
+  void checkPseudoProbe(const object::ELFObjectFileBase *Obj);
 
-  void decodePseudoProbe(const ELFObjectFileBase *Obj);
+  void decodePseudoProbe(const object::ELFObjectFileBase *Obj);
 
   void
-  checkUseFSDiscriminator(const ObjectFile *Obj,
-                          std::map<SectionRef, SectionSymbolsTy> &AllSymbols);
+  checkUseFSDiscriminator(const object::ObjectFile *Obj,
+                          std::map<object::SectionRef, SectionSymbolsTy> &AllSymbols);
 
   // Set up disassembler and related components.
-  void setUpDisassembler(const ObjectFile *Obj);
+  void setUpDisassembler(const object::ObjectFile *Obj);
   symbolize::LLVMSymbolizer::Options getSymbolizerOpts() const;
 
   // Load debug info of subprograms from DWARF section.
-  void loadSymbolsFromDWARF(ObjectFile &Obj);
+  void loadSymbolsFromDWARF(object::ObjectFile &Obj);
 
   // Load debug info from DWARF unit.
   void loadSymbolsFromDWARFUnit(DWARFUnit &CompilationUnit);
 
   // Create elf symbol to its start address mapping.
-  void populateElfSymbolAddressList(const ELFObjectFileBase *O);
+  void populateElfSymbolAddressList(const object::ELFObjectFileBase *O);
 
   // A function may be spilt into multiple non-continuous address ranges. We use
   // this to set whether start a function range is the real entry of the
@@ -341,11 +336,11 @@ class ProfiledBinary {
   void warnNoFuncEntry();
 
   /// Dissassemble the text section and build various address maps.
-  void disassemble(const ObjectFile *O);
+  void disassemble(const object::ObjectFile *O);
 
   /// Helper function to dissassemble the symbol and extract info for unwinding
   bool dissassembleSymbol(std::size_t SI, ArrayRef<uint8_t> Bytes,
-                          SectionSymbolsTy &Symbols, const SectionRef &Section);
+                          SectionSymbolsTy &Symbols, const object::SectionRef &Section);
   /// Symbolize a given instruction pointer and return a full call context.
   SampleContextFrameVector symbolize(const InstructionPointer &IP,
                                      bool UseCanonicalFnName = false,
diff --git a/llvm/tools/llvm-profgen/llvm-profgen.cpp b/llvm/tools/llvm-profgen/llvm-profgen.cpp
index 3b974e25103ad..5464888e77ad5 100644
--- a/llvm/tools/llvm-profgen/llvm-profgen.cpp
+++ b/llvm/tools/llvm-profgen/llvm-profgen.cpp
@@ -21,6 +21,9 @@
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/VirtualFileSystem.h"
 
+using namespace llvm;
+using namespace sampleprof;
+
 static cl::OptionCategory ProfGenCategory("ProfGen Options");
 
 static cl::opt<std::string> PerfScriptFilename(
@@ -71,9 +74,6 @@ extern cl::opt<bool> ShowDisassemblyOnly;
 extern cl::opt<bool> ShowSourceLocations;
 extern cl::opt<bool> SkipSymbolization;
 
-using namespace llvm;
-using namespace sampleprof;
-
 // Validate the command line input.
 static void validateCommandLine() {
   // Allow the missing perfscript if we only use to show binary disassembly.