diff --git a/llvm/include/llvm/XRay/BlockIndexer.h b/llvm/include/llvm/XRay/BlockIndexer.h
index e9782dafed618..155e6bd6fb12a 100644
--- a/llvm/include/llvm/XRay/BlockIndexer.h
+++ b/llvm/include/llvm/XRay/BlockIndexer.h
@@ -19,8 +19,7 @@
 #include <cstdint>
 #include <vector>
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 // The BlockIndexer will gather all related records associated with a
 // process+thread and group them by 'Block'.
@@ -63,7 +62,6 @@ class LLVM_ABI BlockIndexer : public RecordVisitor {
   Error flush();
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_BLOCKINDEXER_H
diff --git a/llvm/include/llvm/XRay/BlockPrinter.h b/llvm/include/llvm/XRay/BlockPrinter.h
index caf78c5c4a5a6..81944a5d05bf5 100644
--- a/llvm/include/llvm/XRay/BlockPrinter.h
+++ b/llvm/include/llvm/XRay/BlockPrinter.h
@@ -18,8 +18,7 @@
 #include "llvm/XRay/FDRRecords.h"
 #include "llvm/XRay/RecordPrinter.h"
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 class LLVM_ABI BlockPrinter : public RecordVisitor {
   enum class State {
@@ -55,7 +54,6 @@ class LLVM_ABI BlockPrinter : public RecordVisitor {
   void reset() { CurrentState = State::Start; }
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_BLOCKPRINTER_H
diff --git a/llvm/include/llvm/XRay/BlockVerifier.h b/llvm/include/llvm/XRay/BlockVerifier.h
index b88785c393e37..5e7b25cc4d0d3 100644
--- a/llvm/include/llvm/XRay/BlockVerifier.h
+++ b/llvm/include/llvm/XRay/BlockVerifier.h
@@ -16,8 +16,7 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/XRay/FDRRecords.h"
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 class LLVM_ABI BlockVerifier : public RecordVisitor {
 public:
@@ -64,7 +63,6 @@ class LLVM_ABI BlockVerifier : public RecordVisitor {
   void reset();
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_BLOCKVERIFIER_H
diff --git a/llvm/include/llvm/XRay/FDRLogBuilder.h b/llvm/include/llvm/XRay/FDRLogBuilder.h
index f07c446ce1e59..5f7b815f4c2a3 100644
--- a/llvm/include/llvm/XRay/FDRLogBuilder.h
+++ b/llvm/include/llvm/XRay/FDRLogBuilder.h
@@ -10,8 +10,7 @@
 
 #include "llvm/XRay/FDRRecords.h"
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 /// The LogBuilder class allows for creating ad-hoc collections of records
 /// through the `add<...>(...)` function. An example use of this API is in
@@ -34,7 +33,6 @@ class LogBuilder {
   std::vector<std::unique_ptr<Record>> consume() { return std::move(Records); }
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_FDRLOGBUILDER_H
diff --git a/llvm/include/llvm/XRay/FDRRecordConsumer.h b/llvm/include/llvm/XRay/FDRRecordConsumer.h
index 473777f0e04f2..13bb711328fdc 100644
--- a/llvm/include/llvm/XRay/FDRRecordConsumer.h
+++ b/llvm/include/llvm/XRay/FDRRecordConsumer.h
@@ -15,8 +15,7 @@
 #include <memory>
 #include <vector>
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 class RecordConsumer {
 public:
@@ -48,7 +47,6 @@ class LLVM_ABI PipelineConsumer : public RecordConsumer {
   Error consume(std::unique_ptr<Record> R) override;
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_FDRRECORDCONSUMER_H
diff --git a/llvm/include/llvm/XRay/FDRRecordProducer.h b/llvm/include/llvm/XRay/FDRRecordProducer.h
index 083b57139d397..b953f62f4eca7 100644
--- a/llvm/include/llvm/XRay/FDRRecordProducer.h
+++ b/llvm/include/llvm/XRay/FDRRecordProducer.h
@@ -14,8 +14,7 @@
 #include "llvm/XRay/XRayRecord.h"
 #include <memory>
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 class RecordProducer {
 public:
@@ -45,7 +44,6 @@ class LLVM_ABI FileBasedRecordProducer : public RecordProducer {
   Expected<std::unique_ptr<Record>> produce() override;
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_FDRRECORDPRODUCER_H
diff --git a/llvm/include/llvm/XRay/FDRRecords.h b/llvm/include/llvm/XRay/FDRRecords.h
index 7ee8db61b2106..91689cae935b1 100644
--- a/llvm/include/llvm/XRay/FDRRecords.h
+++ b/llvm/include/llvm/XRay/FDRRecords.h
@@ -23,8 +23,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/XRay/XRayRecord.h"
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 class RecordVisitor;
 class RecordInitializer;
@@ -444,7 +443,6 @@ class LLVM_ABI RecordInitializer : public RecordVisitor {
   Error visit(TypedEventRecord &) override;
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_FDRRECORDS_H
diff --git a/llvm/include/llvm/XRay/FDRTraceExpander.h b/llvm/include/llvm/XRay/FDRTraceExpander.h
index 197c123fff1e3..ca400c9c567cb 100644
--- a/llvm/include/llvm/XRay/FDRTraceExpander.h
+++ b/llvm/include/llvm/XRay/FDRTraceExpander.h
@@ -17,8 +17,7 @@
 #include "llvm/XRay/FDRRecords.h"
 #include "llvm/XRay/XRayRecord.h"
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 class TraceExpander : public RecordVisitor {
   // Type-erased callback for handling individual XRayRecord instances.
@@ -56,7 +55,6 @@ class TraceExpander : public RecordVisitor {
   Error flush();
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_FDRTRACEEXPANDER_H
diff --git a/llvm/include/llvm/XRay/FDRTraceWriter.h b/llvm/include/llvm/XRay/FDRTraceWriter.h
index a3dc58e03333e..957039d478f3f 100644
--- a/llvm/include/llvm/XRay/FDRTraceWriter.h
+++ b/llvm/include/llvm/XRay/FDRTraceWriter.h
@@ -18,8 +18,7 @@
 #include "llvm/XRay/FDRRecords.h"
 #include "llvm/XRay/XRayRecord.h"
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 /// The FDRTraceWriter allows us to hand-craft an XRay Flight Data Recorder
 /// (FDR) mode log file. This is used primarily for testing, generating
@@ -50,7 +49,6 @@ class LLVM_ABI FDRTraceWriter : public RecordVisitor {
   support::endian::Writer OS;
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_FDRTRACEWRITER_H
diff --git a/llvm/include/llvm/XRay/FileHeaderReader.h b/llvm/include/llvm/XRay/FileHeaderReader.h
index ecdb975a30661..758ca294263b6 100644
--- a/llvm/include/llvm/XRay/FileHeaderReader.h
+++ b/llvm/include/llvm/XRay/FileHeaderReader.h
@@ -19,15 +19,13 @@
 #include "llvm/XRay/XRayRecord.h"
 #include <cstdint>
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 /// Convenience function for loading the file header given a data extractor at a
 /// specified offset.
 LLVM_ABI Expected<XRayFileHeader>
 readBinaryFormatHeader(DataExtractor &HeaderExtractor, uint64_t &OffsetPtr);
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_FILEHEADERREADER_H
diff --git a/llvm/include/llvm/XRay/Graph.h b/llvm/include/llvm/XRay/Graph.h
index 07b418b8cb640..8521e09c33208 100644
--- a/llvm/include/llvm/XRay/Graph.h
+++ b/llvm/include/llvm/XRay/Graph.h
@@ -23,8 +23,7 @@
 #include "llvm/ADT/iterator.h"
 #include "llvm/Support/Error.h"
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 /// A Graph object represents a Directed Graph and is used in XRay to compute
 /// and store function call graphs and associated statistical information.
@@ -485,6 +484,6 @@ class Graph {
     return p;
   }
 };
-}
-}
+} // namespace llvm::xray
+
 #endif
diff --git a/llvm/include/llvm/XRay/InstrumentationMap.h b/llvm/include/llvm/XRay/InstrumentationMap.h
index b5371478680ef..c5e7ebff0e2c1 100644
--- a/llvm/include/llvm/XRay/InstrumentationMap.h
+++ b/llvm/include/llvm/XRay/InstrumentationMap.h
@@ -23,9 +23,7 @@
 #include <unordered_map>
 #include <vector>
 
-namespace llvm {
-
-namespace xray {
+namespace llvm::xray {
 
 // Forward declare to make a friend.
 class InstrumentationMap;
@@ -102,11 +100,11 @@ class InstrumentationMap {
   const SledContainer &sleds() const { return Sleds; };
 };
 
-} // end namespace xray
-
-namespace yaml {
+} // end namespace llvm::xray
 
-template <> struct ScalarEnumerationTraits<xray::SledEntry::FunctionKinds> {
+namespace llvm {
+template <>
+struct yaml::ScalarEnumerationTraits<xray::SledEntry::FunctionKinds> {
   static void enumeration(IO &IO, xray::SledEntry::FunctionKinds &Kind) {
     IO.enumCase(Kind, "function-enter", xray::SledEntry::FunctionKinds::ENTRY);
     IO.enumCase(Kind, "function-exit", xray::SledEntry::FunctionKinds::EXIT);
@@ -118,7 +116,7 @@ template <> struct ScalarEnumerationTraits<xray::SledEntry::FunctionKinds> {
   }
 };
 
-template <> struct MappingTraits<xray::YAMLXRaySledEntry> {
+template <> struct yaml::MappingTraits<xray::YAMLXRaySledEntry> {
   static void mapping(IO &IO, xray::YAMLXRaySledEntry &Entry) {
     IO.mapRequired("id", Entry.FuncId);
     IO.mapRequired("address", Entry.Address);
@@ -131,10 +129,7 @@ template <> struct MappingTraits<xray::YAMLXRaySledEntry> {
 
   static constexpr bool flow = true;
 };
-
-} // end namespace yaml
-
-} // end namespace llvm
+} // namespace llvm
 
 LLVM_YAML_IS_SEQUENCE_VECTOR(xray::YAMLXRaySledEntry)
 
diff --git a/llvm/include/llvm/XRay/Profile.h b/llvm/include/llvm/XRay/Profile.h
index e30c01e489d33..b5b8dd24d1ee4 100644
--- a/llvm/include/llvm/XRay/Profile.h
+++ b/llvm/include/llvm/XRay/Profile.h
@@ -22,8 +22,7 @@
 #include <utility>
 #include <vector>
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 class Profile;
 
@@ -144,7 +143,6 @@ class Profile {
   bool empty() const { return Blocks.empty(); }
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif
diff --git a/llvm/include/llvm/XRay/RecordPrinter.h b/llvm/include/llvm/XRay/RecordPrinter.h
index 5d2c27757255a..3281221d5c294 100644
--- a/llvm/include/llvm/XRay/RecordPrinter.h
+++ b/llvm/include/llvm/XRay/RecordPrinter.h
@@ -17,8 +17,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/XRay/FDRRecords.h"
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 class LLVM_ABI RecordPrinter : public RecordVisitor {
   raw_ostream &OS;
@@ -44,7 +43,6 @@ class LLVM_ABI RecordPrinter : public RecordVisitor {
   Error visit(TypedEventRecord &) override;
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_RECORDPRINTER_H
diff --git a/llvm/include/llvm/XRay/Trace.h b/llvm/include/llvm/XRay/Trace.h
index 5e4e40aa7ca90..13ada22150d91 100644
--- a/llvm/include/llvm/XRay/Trace.h
+++ b/llvm/include/llvm/XRay/Trace.h
@@ -21,8 +21,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/XRay/XRayRecord.h"
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 /// A Trace object represents the records that have been loaded from XRay
 /// log files generated by instrumented binaries. We encapsulate the logic of
@@ -76,7 +75,6 @@ LLVM_ABI Expected<Trace> loadTraceFile(StringRef Filename, bool Sort = false);
 LLVM_ABI Expected<Trace> loadTrace(const DataExtractor &Extractor,
                                    bool Sort = false);
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_TRACE_H
diff --git a/llvm/include/llvm/XRay/XRayRecord.h b/llvm/include/llvm/XRay/XRayRecord.h
index 238bf3daf6ea5..8f3440c8d81f9 100644
--- a/llvm/include/llvm/XRay/XRayRecord.h
+++ b/llvm/include/llvm/XRay/XRayRecord.h
@@ -18,8 +18,7 @@
 #include <vector>
 #include <string>
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 /// XRay traces all have a header providing some top-matter information useful
 /// to help tools determine how to interpret the information available in the
@@ -98,7 +97,6 @@ struct XRayRecord {
   std::string Data;
 };
 
-} // namespace xray
-} // namespace llvm
+} // namespace llvm::xray
 
 #endif // LLVM_XRAY_XRAYRECORD_H
diff --git a/llvm/include/llvm/XRay/YAMLXRayRecord.h b/llvm/include/llvm/XRay/YAMLXRayRecord.h
index 606260693fc4f..6bf4f1d1ae082 100644
--- a/llvm/include/llvm/XRay/YAMLXRayRecord.h
+++ b/llvm/include/llvm/XRay/YAMLXRayRecord.h
@@ -17,8 +17,7 @@
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/XRay/XRayRecord.h"
 
-namespace llvm {
-namespace xray {
+namespace llvm::xray {
 
 struct YAMLXRayFileHeader {
   uint16_t Version;
@@ -46,13 +45,12 @@ struct YAMLXRayTrace {
   std::vector<YAMLXRayRecord> Records;
 };
 
-} // namespace xray
-
-namespace yaml {
+} // namespace llvm::xray
 
+namespace llvm {
 // YAML Traits
 // -----------
-template <> struct ScalarEnumerationTraits<xray::RecordTypes> {
+template <> struct yaml::ScalarEnumerationTraits<xray::RecordTypes> {
   static void enumeration(IO &IO, xray::RecordTypes &Type) {
     IO.enumCase(Type, "function-enter", xray::RecordTypes::ENTER);
     IO.enumCase(Type, "function-exit", xray::RecordTypes::EXIT);
@@ -63,7 +61,7 @@ template <> struct ScalarEnumerationTraits<xray::RecordTypes> {
   }
 };
 
-template <> struct MappingTraits<xray::YAMLXRayFileHeader> {
+template <> struct yaml::MappingTraits<xray::YAMLXRayFileHeader> {
   static void mapping(IO &IO, xray::YAMLXRayFileHeader &Header) {
     IO.mapRequired("version", Header.Version);
     IO.mapRequired("type", Header.Type);
@@ -73,7 +71,7 @@ template <> struct MappingTraits<xray::YAMLXRayFileHeader> {
   }
 };
 
-template <> struct MappingTraits<xray::YAMLXRayRecord> {
+template <> struct yaml::MappingTraits<xray::YAMLXRayRecord> {
   static void mapping(IO &IO, xray::YAMLXRayRecord &Record) {
     IO.mapRequired("type", Record.RecordType);
     IO.mapOptional("func-id", Record.FuncId);
@@ -90,7 +88,7 @@ template <> struct MappingTraits<xray::YAMLXRayRecord> {
   static constexpr bool flow = true;
 };
 
-template <> struct MappingTraits<xray::YAMLXRayTrace> {
+template <> struct yaml::MappingTraits<llvm::xray::YAMLXRayTrace> {
   static void mapping(IO &IO, xray::YAMLXRayTrace &Trace) {
     // A trace file contains two parts, the header and the list of all the
     // trace records.
@@ -98,8 +96,6 @@ template <> struct MappingTraits<xray::YAMLXRayTrace> {
     IO.mapRequired("records", Trace.Records);
   }
 };
-
-} // namespace yaml
 } // namespace llvm
 
 LLVM_YAML_IS_SEQUENCE_VECTOR(xray::YAMLXRayRecord)
diff --git a/llvm/lib/XRay/BlockIndexer.cpp b/llvm/lib/XRay/BlockIndexer.cpp
index f4ba0eb5bda9c..d0c68539e8180 100644
--- a/llvm/lib/XRay/BlockIndexer.cpp
+++ b/llvm/lib/XRay/BlockIndexer.cpp
@@ -12,8 +12,8 @@
 //===----------------------------------------------------------------------===//
 #include "llvm/XRay/BlockIndexer.h"
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 Error BlockIndexer::visit(BufferExtents &) { return Error::success(); }
 
@@ -89,6 +89,3 @@ Error BlockIndexer::flush() {
   CurrentBlock.WallclockTime = nullptr;
   return Error::success();
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/BlockPrinter.cpp b/llvm/lib/XRay/BlockPrinter.cpp
index 63a60c3c56a38..d85be5bc664d2 100644
--- a/llvm/lib/XRay/BlockPrinter.cpp
+++ b/llvm/lib/XRay/BlockPrinter.cpp
@@ -7,8 +7,8 @@
 //===----------------------------------------------------------------------===//
 #include "llvm/XRay/BlockPrinter.h"
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 Error BlockPrinter::visit(BufferExtents &R) {
   OS << "\n[New Block]\n";
@@ -108,6 +108,3 @@ Error BlockPrinter::visit(EndBufferRecord &R) {
     auto E = RP.visit(R);
     return E;
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/BlockVerifier.cpp b/llvm/lib/XRay/BlockVerifier.cpp
index 99f255ea66887..e39f6b6f44b6f 100644
--- a/llvm/lib/XRay/BlockVerifier.cpp
+++ b/llvm/lib/XRay/BlockVerifier.cpp
@@ -10,19 +10,18 @@
 
 #include <bitset>
 
-namespace llvm {
-namespace xray {
-namespace {
+using namespace llvm;
+using namespace llvm::xray;
 
-constexpr unsigned long long mask(BlockVerifier::State S) {
+static constexpr unsigned long long mask(BlockVerifier::State S) {
   return 1uLL << static_cast<std::size_t>(S);
 }
 
-constexpr std::size_t number(BlockVerifier::State S) {
+static constexpr std::size_t number(BlockVerifier::State S) {
   return static_cast<std::size_t>(S);
 }
 
-StringRef recordToString(BlockVerifier::State R) {
+static StringRef recordToString(BlockVerifier::State R) {
   switch (R) {
   case BlockVerifier::State::BufferExtents:
     return "BufferExtents";
@@ -53,6 +52,8 @@ StringRef recordToString(BlockVerifier::State R) {
   llvm_unreachable("Unkown state!");
 }
 
+namespace {
+
 struct Transition {
   BlockVerifier::State From;
   std::bitset<number(BlockVerifier::State::StateMax)> ToStates;
@@ -133,7 +134,7 @@ Error BlockVerifier::transition(State To) {
 
   CurrentRecord = To;
   return Error::success();
-} // namespace xray
+}
 
 Error BlockVerifier::visit(BufferExtents &) {
   return transition(State::BufferExtents);
@@ -201,6 +202,3 @@ Error BlockVerifier::verify() {
 }
 
 void BlockVerifier::reset() { CurrentRecord = State::Unknown; }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/FDRRecordProducer.cpp b/llvm/lib/XRay/FDRRecordProducer.cpp
index 479b710444be8..0f4eed13525e8 100644
--- a/llvm/lib/XRay/FDRRecordProducer.cpp
+++ b/llvm/lib/XRay/FDRRecordProducer.cpp
@@ -10,8 +10,8 @@
 
 #include <cstdint>
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 namespace {
 
@@ -31,8 +31,9 @@ enum MetadataRecordKinds : uint8_t {
   // This is an end marker, used to identify the upper bound for this enum.
   EnumEndMarker,
 };
+} // namespace
 
-Expected<std::unique_ptr<Record>>
+static Expected<std::unique_ptr<Record>>
 metadataRecordType(const XRayFileHeader &Header, uint8_t T) {
 
   if (T >= static_cast<uint8_t>(MetadataRecordKinds::EnumEndMarker))
@@ -72,12 +73,10 @@ metadataRecordType(const XRayFileHeader &Header, uint8_t T) {
   llvm_unreachable("Unhandled MetadataRecordKinds enum value");
 }
 
-constexpr bool isMetadataIntroducer(uint8_t FirstByte) {
+static constexpr bool isMetadataIntroducer(uint8_t FirstByte) {
   return FirstByte & 0x01u;
 }
 
-} // namespace
-
 Expected<std::unique_ptr<Record>>
 FileBasedRecordProducer::findNextBufferExtent() {
   // We seek one byte at a time until we find a suitable buffer extents metadata
@@ -193,6 +192,3 @@ Expected<std::unique_ptr<Record>> FileBasedRecordProducer::produce() {
   assert(R != nullptr);
   return std::move(R);
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/FDRRecords.cpp b/llvm/lib/XRay/FDRRecords.cpp
index ff315d35417d6..a18f733ef73bf 100644
--- a/llvm/lib/XRay/FDRRecords.cpp
+++ b/llvm/lib/XRay/FDRRecords.cpp
@@ -12,8 +12,8 @@
 //===----------------------------------------------------------------------===//
 #include "llvm/XRay/FDRRecords.h"
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 Error BufferExtents::apply(RecordVisitor &V) { return V.visit(*this); }
 Error WallclockRecord::apply(RecordVisitor &V) { return V.visit(*this); }
@@ -61,6 +61,3 @@ StringRef Record::kindToString(RecordKind K) {
   }
   return "Unknown";
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/FDRTraceExpander.cpp b/llvm/lib/XRay/FDRTraceExpander.cpp
index b68e997fe7063..991e6e5127aa0 100644
--- a/llvm/lib/XRay/FDRTraceExpander.cpp
+++ b/llvm/lib/XRay/FDRTraceExpander.cpp
@@ -7,8 +7,8 @@
 //===----------------------------------------------------------------------===//
 #include "llvm/XRay/FDRTraceExpander.h"
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 void TraceExpander::resetCurrentRecord() {
   if (BuildingRecord)
@@ -126,6 +126,3 @@ Error TraceExpander::flush() {
   resetCurrentRecord();
   return Error::success();
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/FDRTraceWriter.cpp b/llvm/lib/XRay/FDRTraceWriter.cpp
index fb591252ffa3e..3e320a64da9fd 100644
--- a/llvm/lib/XRay/FDRTraceWriter.cpp
+++ b/llvm/lib/XRay/FDRTraceWriter.cpp
@@ -12,8 +12,8 @@
 #include "llvm/XRay/FDRTraceWriter.h"
 #include <tuple>
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 namespace {
 
@@ -37,9 +37,10 @@ template <size_t Index> struct IndexedWriter {
     return 0;
   }
 };
+} // namespace
 
 template <uint8_t Kind, class... Values>
-Error writeMetadata(support::endian::Writer &OS, Values &&... Ds) {
+static Error writeMetadata(support::endian::Writer &OS, Values &&...Ds) {
   // The first bit in the first byte of metadata records is always set to 1, so
   // we ensure this is the case when we write out the first byte of the record.
   uint8_t FirstByte = (static_cast<uint8_t>(Kind) << 1) | uint8_t{0x01u};
@@ -54,8 +55,6 @@ Error writeMetadata(support::endian::Writer &OS, Values &&... Ds) {
   return Error::success();
 }
 
-} // namespace
-
 FDRTraceWriter::FDRTraceWriter(raw_ostream &O, const XRayFileHeader &H)
     : OS(O, llvm::endianness::native) {
   // We need to re-construct a header, by writing the fields we care about for
@@ -146,6 +145,3 @@ Error FDRTraceWriter::visit(FunctionRecord &R) {
   OS.write(R.delta());
   return Error::success();
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/FileHeaderReader.cpp b/llvm/lib/XRay/FileHeaderReader.cpp
index 6b6daf9deba59..681cef7122f30 100644
--- a/llvm/lib/XRay/FileHeaderReader.cpp
+++ b/llvm/lib/XRay/FileHeaderReader.cpp
@@ -7,12 +7,13 @@
 //===----------------------------------------------------------------------===//
 #include "llvm/XRay/FileHeaderReader.h"
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 // Populates the FileHeader reference by reading the first 32 bytes of the file.
-Expected<XRayFileHeader> readBinaryFormatHeader(DataExtractor &HeaderExtractor,
-                                                uint64_t &OffsetPtr) {
+Expected<XRayFileHeader>
+xray::readBinaryFormatHeader(DataExtractor &HeaderExtractor,
+                             uint64_t &OffsetPtr) {
   // FIXME: Maybe deduce whether the data is little or big-endian using some
   // magic bytes in the beginning of the file?
 
@@ -68,6 +69,3 @@ Expected<XRayFileHeader> readBinaryFormatHeader(DataExtractor &HeaderExtractor,
   OffsetPtr += 16;
   return std::move(FileHeader);
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/LogBuilderConsumer.cpp b/llvm/lib/XRay/LogBuilderConsumer.cpp
index ffb49f9eb4e98..f0fc3360b28e4 100644
--- a/llvm/lib/XRay/LogBuilderConsumer.cpp
+++ b/llvm/lib/XRay/LogBuilderConsumer.cpp
@@ -7,8 +7,8 @@
 //===----------------------------------------------------------------------===//
 #include "llvm/XRay/FDRRecordConsumer.h"
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 Error LogBuilderConsumer::consume(std::unique_ptr<Record> R) {
   if (!R)
@@ -32,6 +32,3 @@ Error PipelineConsumer::consume(std::unique_ptr<Record> R) {
     Result = joinErrors(std::move(Result), R->apply(*V));
   return Result;
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/Profile.cpp b/llvm/lib/XRay/Profile.cpp
index 1b340e54c9dbb..ecb767bfc2c2a 100644
--- a/llvm/lib/XRay/Profile.cpp
+++ b/llvm/lib/XRay/Profile.cpp
@@ -18,8 +18,8 @@
 #include "llvm/XRay/Trace.h"
 #include <memory>
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 Profile::Profile(const Profile &O) {
   // We need to re-create all the tries from the original (O), into the current
@@ -46,6 +46,7 @@ struct BlockHeader {
   uint32_t Number;
   uint64_t Thread;
 };
+} // namespace
 
 static Expected<BlockHeader> readBlockHeader(DataExtractor &Extractor,
                                              uint64_t &Offset) {
@@ -115,8 +116,6 @@ static Expected<Profile::Data> readData(DataExtractor &Extractor,
   return D;
 }
 
-} // namespace
-
 Error Profile::addBlock(Block &&B) {
   if (B.PathData.empty())
     return make_error<StringError>(
@@ -189,7 +188,7 @@ Profile::PathID Profile::internPath(ArrayRef<FuncID> P) {
   return Node->ID;
 }
 
-Profile mergeProfilesByThread(const Profile &L, const Profile &R) {
+Profile xray::mergeProfilesByThread(const Profile &L, const Profile &R) {
   Profile Merged;
   using PathDataMap = DenseMap<Profile::PathID, Profile::Data>;
   using PathDataMapPtr = std::unique_ptr<PathDataMap>;
@@ -228,7 +227,7 @@ Profile mergeProfilesByThread(const Profile &L, const Profile &R) {
   return Merged;
 }
 
-Profile mergeProfilesByStack(const Profile &L, const Profile &R) {
+Profile xray::mergeProfilesByStack(const Profile &L, const Profile &R) {
   Profile Merged;
   using PathDataMap = DenseMap<Profile::PathID, Profile::Data>;
   PathDataMap PathData;
@@ -258,7 +257,7 @@ Profile mergeProfilesByStack(const Profile &L, const Profile &R) {
   return Merged;
 }
 
-Expected<Profile> loadProfile(StringRef Filename) {
+Expected<Profile> xray::loadProfile(StringRef Filename) {
   Expected<sys::fs::file_t> FdOrErr = sys::fs::openNativeFileForRead(Filename);
   if (!FdOrErr)
     return FdOrErr.takeError();
@@ -322,7 +321,7 @@ struct StackEntry {
 
 } // namespace
 
-Expected<Profile> profileFromTrace(const Trace &T) {
+Expected<Profile> xray::profileFromTrace(const Trace &T) {
   Profile P;
 
   // The implementation of the algorithm re-creates the execution of
@@ -397,6 +396,3 @@ Expected<Profile> profileFromTrace(const Trace &T) {
 
   return P;
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/RecordInitializer.cpp b/llvm/lib/XRay/RecordInitializer.cpp
index 68ab3db06208d..83d5f14b10504 100644
--- a/llvm/lib/XRay/RecordInitializer.cpp
+++ b/llvm/lib/XRay/RecordInitializer.cpp
@@ -7,8 +7,8 @@
 //===----------------------------------------------------------------------===//
 #include "llvm/XRay/FDRRecords.h"
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 Error RecordInitializer::visit(BufferExtents &R) {
   if (!E.isValidOffsetForDataOfSize(OffsetPtr, sizeof(uint64_t)))
@@ -426,6 +426,3 @@ Error RecordInitializer::visit(FunctionRecord &R) {
   assert(FunctionRecord::kFunctionRecordSize == (OffsetPtr - BeginOffset));
   return Error::success();
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/RecordPrinter.cpp b/llvm/lib/XRay/RecordPrinter.cpp
index 32d42104db95c..b9b7a16501591 100644
--- a/llvm/lib/XRay/RecordPrinter.cpp
+++ b/llvm/lib/XRay/RecordPrinter.cpp
@@ -9,8 +9,8 @@
 
 #include "llvm/Support/FormatVariadic.h"
 
-namespace llvm {
-namespace xray {
+using namespace llvm;
+using namespace llvm::xray;
 
 Error RecordPrinter::visit(BufferExtents &R) {
   OS << formatv("<Buffer: size = {0} bytes>", R.size()) << Delim;
@@ -103,6 +103,3 @@ Error RecordPrinter::visit(FunctionRecord &R) {
   OS << Delim;
   return Error::success();
 }
-
-} // namespace xray
-} // namespace llvm
diff --git a/llvm/lib/XRay/Trace.cpp b/llvm/lib/XRay/Trace.cpp
index 74515b16417da..14a3f01be66bd 100644
--- a/llvm/lib/XRay/Trace.cpp
+++ b/llvm/lib/XRay/Trace.cpp
@@ -29,11 +29,9 @@ using namespace llvm;
 using namespace llvm::xray;
 using llvm::yaml::Input;
 
-namespace {
-
-Error loadNaiveFormatLog(StringRef Data, bool IsLittleEndian,
-                         XRayFileHeader &FileHeader,
-                         std::vector<XRayRecord> &Records) {
+static Error loadNaiveFormatLog(StringRef Data, bool IsLittleEndian,
+                                XRayFileHeader &FileHeader,
+                                std::vector<XRayRecord> &Records) {
   if (Data.size() < 32)
     return make_error<StringError>(
         "Not enough bytes for an XRay log.",
@@ -265,8 +263,9 @@ Error loadNaiveFormatLog(StringRef Data, bool IsLittleEndian,
 /// what FunctionRecord instances use, and we no longer need to include the CPU
 /// id in the CustomEventRecord.
 ///
-Error loadFDRLog(StringRef Data, bool IsLittleEndian,
-                 XRayFileHeader &FileHeader, std::vector<XRayRecord> &Records) {
+static Error loadFDRLog(StringRef Data, bool IsLittleEndian,
+                        XRayFileHeader &FileHeader,
+                        std::vector<XRayRecord> &Records) {
 
   if (Data.size() < 32)
     return createStringError(std::make_error_code(std::errc::invalid_argument),
@@ -348,8 +347,8 @@ Error loadFDRLog(StringRef Data, bool IsLittleEndian,
   return Error::success();
 }
 
-Error loadYAMLLog(StringRef Data, XRayFileHeader &FileHeader,
-                  std::vector<XRayRecord> &Records) {
+static Error loadYAMLLog(StringRef Data, XRayFileHeader &FileHeader,
+                         std::vector<XRayRecord> &Records) {
   YAMLXRayTrace Trace;
   Input In(Data);
   In >> Trace;
@@ -376,7 +375,6 @@ Error loadYAMLLog(StringRef Data, XRayFileHeader &FileHeader,
                  });
   return Error::success();
 }
-} // namespace
 
 Expected<Trace> llvm::xray::loadTraceFile(StringRef Filename, bool Sort) {
   Expected<sys::fs::file_t> FdOrErr = sys::fs::openNativeFileForRead(Filename);