diff --git a/lld/wasm/InputFiles.h b/lld/wasm/InputFiles.h
--- a/lld/wasm/InputFiles.h
+++ b/lld/wasm/InputFiles.h
@@ -98,7 +98,6 @@
 
   const WasmSection *CodeSection = nullptr;
   const WasmSection *DataSection = nullptr;
-  const WasmSection *ProducersSection = nullptr;
 
   // Maps input type indices to output type indices
   std::vector<uint32_t> TypeMap;
diff --git a/lld/wasm/InputFiles.cpp b/lld/wasm/InputFiles.cpp
--- a/lld/wasm/InputFiles.cpp
+++ b/lld/wasm/InputFiles.cpp
@@ -239,8 +239,6 @@
       CustomSections.emplace_back(make<InputSection>(Section, this));
       CustomSections.back()->setRelocations(Section.Relocations);
       CustomSectionsByIndex[SectionIndex] = CustomSections.back();
-      if (Section.Name == "producers")
-        ProducersSection = &Section;
     }
     SectionIndex++;
   }
diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
--- a/lld/wasm/Writer.cpp
+++ b/lld/wasm/Writer.cpp
@@ -20,6 +20,7 @@
 #include "lld/Common/Strings.h"
 #include "lld/Common/Threads.h"
 #include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/BinaryFormat/Wasm.h"
@@ -66,6 +67,7 @@
   void createCtorFunction();
   void calculateInitFunctions();
   void assignIndexes();
+  void calculateTargetFeatures();
   void calculateImports();
   void calculateExports();
   void calculateCustomSections();
@@ -97,6 +99,7 @@
   void createLinkingSection();
   void createNameSection();
   void createProducersSection();
+  void createTargetFeaturesSection();
 
   void writeHeader();
   void writeSections();
@@ -127,6 +130,7 @@
 
   llvm::StringMap<std::vector<InputSection *>> CustomSectionMapping;
   llvm::StringMap<SectionSymbol *> CustomSectionSymbols;
+  llvm::SmallSet<std::string, 8> TargetFeatures;
 
   // Elements that are used to construct the final output
   std::string Header;
@@ -339,7 +343,7 @@
       // These custom sections are known the linker and synthesized rather than
       // blindly copied
       if (Name == "linking" || Name == "name" || Name == "producers" ||
-          Name.startswith("reloc."))
+          Name == "target_features" || Name.startswith("reloc."))
         continue;
       // .. or it is a debug section
       if (StripDebug && Name.startswith(".debug_"))
@@ -694,6 +698,23 @@
   }
 }
 
+void Writer::createTargetFeaturesSection() {
+  if (TargetFeatures.size() == 0)
+    return;
+
+  SmallVector<std::string, 8> Emitted(TargetFeatures.begin(),
+                                      TargetFeatures.end());
+  std::sort(Emitted.begin(), Emitted.end());
+  SyntheticSection *Section =
+      createSyntheticSection(WASM_SEC_CUSTOM, "target_features");
+  auto &OS = Section->getStream();
+  writeUleb128(OS, Emitted.size(), "feature count");
+  for (auto &Feature : Emitted) {
+    writeU8(OS, WASM_FEATURE_PREFIX_USED, "feature used prefix");
+    writeStr(OS, Feature, "feature name");
+  }
+}
+
 void Writer::writeHeader() {
   memcpy(Buffer->getBufferStart(), Header.data(), Header.size());
 }
@@ -837,8 +858,10 @@
   if (!Config->StripDebug && !Config->StripAll)
     createNameSection();
 
-  if (!Config->StripAll)
+  if (!Config->StripAll) {
     createProducersSection();
+    createTargetFeaturesSection();
+  }
 
   for (OutputSection *S : OutputSections) {
     S->setOffset(FileSize);
@@ -847,6 +870,48 @@
   }
 }
 
+void Writer::calculateTargetFeatures() {
+  SmallSet<std::string, 8> Required;
+  SmallSet<std::string, 8> Disallowed;
+
+  // Find the sets of used, required, and disallowed features
+  for (ObjFile *File : Symtab->ObjectFiles) {
+    for (auto &Feature : File->getWasmObj()->getTargetFeatures()) {
+      switch (Feature.Prefix) {
+      case WASM_FEATURE_PREFIX_USED:
+        TargetFeatures.insert(Feature.Name);
+        break;
+      case WASM_FEATURE_PREFIX_REQUIRED:
+        TargetFeatures.insert(Feature.Name);
+        Required.insert(Feature.Name);
+        break;
+      case WASM_FEATURE_PREFIX_DISALLOWED:
+        Disallowed.insert(Feature.Name);
+        break;
+      default:
+        error("Unrecognized feature policy prefix " +
+              std::to_string(Feature.Prefix));
+      }
+    }
+  }
+
+  // Validate the required and disallowed constraints for each file
+  for (ObjFile *File : Symtab->ObjectFiles) {
+    SmallSet<std::string, 8> ObjectFeatures;
+    for (auto &Feature : File->getWasmObj()->getTargetFeatures()) {
+      if (Feature.Prefix == WASM_FEATURE_PREFIX_DISALLOWED)
+        continue;
+      ObjectFeatures.insert(Feature.Name);
+      if (Disallowed.count(Feature.Name))
+        error("Target feature \"" + Feature.Name + "\" is disallowed");
+    }
+    for (auto &Feature : Required) {
+      if (!ObjectFeatures.count(Feature))
+        error(Twine("Missing required target feature \"") + Feature + "\"");
+    }
+  }
+}
+
 void Writer::calculateImports() {
   for (Symbol *Sym : Symtab->getSymbols()) {
     if (!Sym->isUndefined())
@@ -1199,6 +1264,8 @@
   if (!Config->Pic)
     TableBase = 1;
 
+  log("-- calculateTargetFeatures");
+  calculateTargetFeatures();
   log("-- calculateImports");
   calculateImports();
   log("-- assignIndexes");
diff --git a/llvm/include/llvm/BinaryFormat/Wasm.h b/llvm/include/llvm/BinaryFormat/Wasm.h
--- a/llvm/include/llvm/BinaryFormat/Wasm.h
+++ b/llvm/include/llvm/BinaryFormat/Wasm.h
@@ -48,6 +48,11 @@
   std::vector<std::pair<std::string, std::string>> SDKs;
 };
 
+struct WasmFeatureEntry {
+  uint8_t Prefix;
+  std::string Name;
+};
+
 struct WasmExport {
   StringRef Name;
   uint8_t Kind;
@@ -253,6 +258,13 @@
   WASM_SEGMENT_HAS_MEMINDEX = 0x02,
 };
 
+// Feature policy prefixes used in the custom "target_features" section
+enum : uint8_t {
+  WASM_FEATURE_PREFIX_USED = '+',
+  WASM_FEATURE_PREFIX_REQUIRED = '=',
+  WASM_FEATURE_PREFIX_DISALLOWED = '-',
+};
+
 // Kind codes used in the custom "name" section
 enum : unsigned {
   WASM_NAMES_FUNCTION = 0x1,
diff --git a/llvm/include/llvm/Object/Wasm.h b/llvm/include/llvm/Object/Wasm.h
--- a/llvm/include/llvm/Object/Wasm.h
+++ b/llvm/include/llvm/Object/Wasm.h
@@ -130,6 +130,9 @@
 
   const wasm::WasmDylinkInfo &dylinkInfo() const { return DylinkInfo; }
   const wasm::WasmProducerInfo &getProducerInfo() const { return ProducerInfo; }
+  ArrayRef<wasm::WasmFeatureEntry> getTargetFeatures() const {
+    return TargetFeatures;
+  }
   ArrayRef<wasm::WasmSignature> types() const { return Signatures; }
   ArrayRef<uint32_t> functionTypes() const { return FunctionTypes; }
   ArrayRef<wasm::WasmImport> imports() const { return Imports; }
@@ -252,12 +255,14 @@
   Error parseLinkingSectionSymtab(ReadContext &Ctx);
   Error parseLinkingSectionComdat(ReadContext &Ctx);
   Error parseProducersSection(ReadContext &Ctx);
+  Error parseTargetFeaturesSection(ReadContext &Ctx);
   Error parseRelocSection(StringRef Name, ReadContext &Ctx);
 
   wasm::WasmObjectHeader Header;
   std::vector<WasmSection> Sections;
   wasm::WasmDylinkInfo DylinkInfo;
   wasm::WasmProducerInfo ProducerInfo;
+  std::vector<wasm::WasmFeatureEntry> TargetFeatures;
   std::vector<wasm::WasmSignature> Signatures;
   std::vector<uint32_t> FunctionTypes;
   std::vector<wasm::WasmTable> Tables;
@@ -318,6 +323,8 @@
     WASM_SEC_ORDER_NAME,
     // "producers" section must appear after "name" section.
     WASM_SEC_ORDER_PRODUCERS,
+    // "target_features" section must appear after producers section
+    WASM_SEC_ORDER_TARGET_FEATURES,
 
     // Must be last
     WASM_NUM_SEC_ORDERS
diff --git a/llvm/include/llvm/ObjectYAML/WasmYAML.h b/llvm/include/llvm/ObjectYAML/WasmYAML.h
--- a/llvm/include/llvm/ObjectYAML/WasmYAML.h
+++ b/llvm/include/llvm/ObjectYAML/WasmYAML.h
@@ -38,6 +38,7 @@
 LLVM_YAML_STRONG_TYPEDEF(uint32_t, SegmentFlags)
 LLVM_YAML_STRONG_TYPEDEF(uint32_t, LimitFlags)
 LLVM_YAML_STRONG_TYPEDEF(uint32_t, ComdatKind)
+LLVM_YAML_STRONG_TYPEDEF(uint32_t, FeaturePolicyPrefix)
 
 struct FileHeader {
   yaml::Hex32 Version;
@@ -128,6 +129,11 @@
   std::string Version;
 };
 
+struct FeatureEntry {
+  FeaturePolicyPrefix Prefix;
+  std::string Name;
+};
+
 struct SegmentInfo {
   uint32_t Index;
   StringRef Name;
@@ -242,6 +248,17 @@
   std::vector<ProducerEntry> SDKs;
 };
 
+struct TargetFeaturesSection : CustomSection {
+  TargetFeaturesSection() : CustomSection("target_features") {}
+
+  static bool classof(const Section *S) {
+    auto C = dyn_cast<CustomSection>(S);
+    return C && C->Name == "target_features";
+  }
+
+  std::vector<FeatureEntry> Features;
+};
+
 struct TypeSection : Section {
   TypeSection() : Section(wasm::WASM_SEC_TYPE) {}
 
@@ -385,6 +402,7 @@
 LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::WasmYAML::Relocation)
 LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::WasmYAML::NameEntry)
 LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::WasmYAML::ProducerEntry)
+LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::WasmYAML::FeatureEntry)
 LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::WasmYAML::SegmentInfo)
 LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::WasmYAML::SymbolInfo)
 LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::WasmYAML::InitFunction)
@@ -467,6 +485,14 @@
   static void mapping(IO &IO, WasmYAML::ProducerEntry &ProducerEntry);
 };
 
+template <> struct ScalarEnumerationTraits<WasmYAML::FeaturePolicyPrefix> {
+  static void enumeration(IO &IO, WasmYAML::FeaturePolicyPrefix &Prefix);
+};
+
+template <> struct MappingTraits<WasmYAML::FeatureEntry> {
+  static void mapping(IO &IO, WasmYAML::FeatureEntry &FeatureEntry);
+};
+
 template <> struct MappingTraits<WasmYAML::SegmentInfo> {
   static void mapping(IO &IO, WasmYAML::SegmentInfo &SegmentInfo);
 };
diff --git a/llvm/lib/MC/MCParser/WasmAsmParser.cpp b/llvm/lib/MC/MCParser/WasmAsmParser.cpp
--- a/llvm/lib/MC/MCParser/WasmAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/WasmAsmParser.cpp
@@ -135,9 +135,10 @@
       SectionKind Kind;
     };
     static SectionType SectionTypes[] = {
-        { ".text", SectionKind::getText() },
-        { ".rodata", SectionKind::getReadOnly() },
-        { ".data", SectionKind::getData() },
+        {".text", SectionKind::getText()},
+        {".rodata", SectionKind::getReadOnly()},
+        {".data", SectionKind::getData()},
+        {".custom_section", SectionKind::getMetadata()},
         // TODO: add more types.
     };
     for (size_t I = 0; I < sizeof(SectionTypes) / sizeof(SectionType); I++) {
diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
--- a/llvm/lib/MC/WasmObjectWriter.cpp
+++ b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -250,6 +250,7 @@
   // section.
   std::vector<WasmCustomSection> CustomSections;
   std::unique_ptr<WasmCustomSection> ProducersSection;
+  std::unique_ptr<WasmCustomSection> TargetFeaturesSection;
   // Relocations for fixing up references in the custom sections.
   DenseMap<const MCSectionWasm *, std::vector<WasmRelocationEntry>>
       CustomSectionsRelocations;
@@ -291,6 +292,7 @@
     DataLocations.clear();
     CustomSections.clear();
     ProducersSection.reset();
+    TargetFeaturesSection.reset();
     CustomSectionsRelocations.clear();
     SignatureIndices.clear();
     Signatures.clear();
@@ -1286,11 +1288,16 @@
                              Twine(SectionName));
       }
 
-      // Separate out the producers section
+      // Separate out the producers and target features sections
       if (Name == "producers") {
         ProducersSection = llvm::make_unique<WasmCustomSection>(Name, &Section);
         continue;
       }
+      if (Name == "target_features") {
+        TargetFeaturesSection =
+            llvm::make_unique<WasmCustomSection>(Name, &Section);
+        continue;
+      }
 
       CustomSections.emplace_back(Name, &Section);
     }
@@ -1593,6 +1600,8 @@
   writeCustomRelocSections();
   if (ProducersSection)
     writeCustomSection(*ProducersSection, Asm, Layout);
+  if (TargetFeaturesSection)
+    writeCustomSection(*TargetFeaturesSection, Asm, Layout);
 
   // TODO: Translate the .comment section to the output.
   return W.OS.tell() - StartOffset;
diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
--- a/llvm/lib/Object/WasmObjectFile.cpp
+++ b/llvm/lib/Object/WasmObjectFile.cpp
@@ -674,7 +674,7 @@
 }
 
 Error WasmObjectFile::parseProducersSection(ReadContext &Ctx) {
-  llvm::SmallSet<StringRef, 3> FieldsSeen;
+  llvm::SmallSet<std::string, 3> FieldsSeen;
   uint32_t Fields = readVaruint32(Ctx);
   for (size_t I = 0; I < Fields; ++I) {
     StringRef FieldName = readString(Ctx);
@@ -714,6 +714,36 @@
   return Error::success();
 }
 
+Error WasmObjectFile::parseTargetFeaturesSection(ReadContext &Ctx) {
+  llvm::SmallSet<std::string, 8> FeaturesSeen;
+  uint32_t FeatureCount = readVaruint32(Ctx);
+  for (size_t I = 0; I < FeatureCount; ++I) {
+    wasm::WasmFeatureEntry Feature;
+    Feature.Prefix = readUint8(Ctx);
+    switch (Feature.Prefix) {
+    case wasm::WASM_FEATURE_PREFIX_USED:
+    case wasm::WASM_FEATURE_PREFIX_REQUIRED:
+    case wasm::WASM_FEATURE_PREFIX_DISALLOWED:
+      break;
+    default:
+      return make_error<GenericBinaryError>("Unknown feature policy prefix",
+                                            object_error::parse_failed);
+    }
+    Feature.Name = readString(Ctx);
+    if (!FeaturesSeen.insert(Feature.Name).second)
+      return make_error<GenericBinaryError>(
+          "Target features section contains repeated feature \"" +
+              Feature.Name + "\"",
+          object_error::parse_failed);
+    TargetFeatures.push_back(Feature);
+  }
+  if (Ctx.Ptr != Ctx.End)
+    return make_error<GenericBinaryError>(
+        "Target features section ended prematurely",
+        object_error::parse_failed);
+  return Error::success();
+}
+
 Error WasmObjectFile::parseRelocSection(StringRef Name, ReadContext &Ctx) {
   uint32_t SectionIndex = readVaruint32(Ctx);
   if (SectionIndex >= Sections.size())
@@ -815,6 +845,9 @@
   } else if (Sec.Name == "producers") {
     if (Error Err = parseProducersSection(Ctx))
       return Err;
+  } else if (Sec.Name == "target_features") {
+    if (Error Err = parseTargetFeaturesSection(Ctx))
+      return Err;
   } else if (Sec.Name.startswith("reloc.")) {
     if (Error Err = parseRelocSection(Sec.Name, Ctx))
       return Err;
@@ -1527,6 +1560,7 @@
         .StartsWith("reloc.", WASM_SEC_ORDER_RELOC)
         .Case("name", WASM_SEC_ORDER_NAME)
         .Case("producers", WASM_SEC_ORDER_PRODUCERS)
+        .Case("target_features", WASM_SEC_ORDER_TARGET_FEATURES)
         .Default(WASM_SEC_ORDER_NONE);
   case wasm::WASM_SEC_TYPE:
     return WASM_SEC_ORDER_TYPE;
@@ -1562,28 +1596,36 @@
 // Represents the edges in a directed graph where any node B reachable from node
 // A is not allowed to appear before A in the section ordering, but may appear
 // afterward.
-int WasmSectionOrderChecker::DisallowedPredecessors[WASM_NUM_SEC_ORDERS][WASM_NUM_SEC_ORDERS] = {
-  {}, // WASM_SEC_ORDER_NONE
-  {WASM_SEC_ORDER_TYPE, WASM_SEC_ORDER_IMPORT}, // WASM_SEC_ORDER_TYPE,
-  {WASM_SEC_ORDER_IMPORT, WASM_SEC_ORDER_FUNCTION}, // WASM_SEC_ORDER_IMPORT,
-  {WASM_SEC_ORDER_FUNCTION, WASM_SEC_ORDER_TABLE}, // WASM_SEC_ORDER_FUNCTION,
-  {WASM_SEC_ORDER_TABLE, WASM_SEC_ORDER_MEMORY}, // WASM_SEC_ORDER_TABLE,
-  {WASM_SEC_ORDER_MEMORY, WASM_SEC_ORDER_GLOBAL}, // WASM_SEC_ORDER_MEMORY,
-  {WASM_SEC_ORDER_GLOBAL, WASM_SEC_ORDER_EVENT}, // WASM_SEC_ORDER_GLOBAL,
-  {WASM_SEC_ORDER_EVENT, WASM_SEC_ORDER_EXPORT}, // WASM_SEC_ORDER_EVENT,
-  {WASM_SEC_ORDER_EXPORT, WASM_SEC_ORDER_START}, // WASM_SEC_ORDER_EXPORT,
-  {WASM_SEC_ORDER_START, WASM_SEC_ORDER_ELEM}, // WASM_SEC_ORDER_START,
-  {WASM_SEC_ORDER_ELEM, WASM_SEC_ORDER_DATACOUNT}, // WASM_SEC_ORDER_ELEM,
-  {WASM_SEC_ORDER_DATACOUNT, WASM_SEC_ORDER_CODE}, // WASM_SEC_ORDER_DATACOUNT,
-  {WASM_SEC_ORDER_CODE, WASM_SEC_ORDER_DATA}, // WASM_SEC_ORDER_CODE,
-  {WASM_SEC_ORDER_DATA, WASM_SEC_ORDER_LINKING}, // WASM_SEC_ORDER_DATA,
-
-  // Custom Sections
-  {WASM_SEC_ORDER_DYLINK, WASM_SEC_ORDER_TYPE}, // WASM_SEC_ORDER_DYLINK,
-  {WASM_SEC_ORDER_LINKING, WASM_SEC_ORDER_RELOC, WASM_SEC_ORDER_NAME}, // WASM_SEC_ORDER_LINKING,
-  {}, // WASM_SEC_ORDER_RELOC (can be repeated),
-  {WASM_SEC_ORDER_NAME, WASM_SEC_ORDER_PRODUCERS}, // WASM_SEC_ORDER_NAME,
-  {WASM_SEC_ORDER_PRODUCERS}, // WASM_SEC_ORDER_PRODUCERS,
+int WasmSectionOrderChecker::DisallowedPredecessors
+    [WASM_NUM_SEC_ORDERS][WASM_NUM_SEC_ORDERS] = {
+        {},                                           // WASM_SEC_ORDER_NONE
+        {WASM_SEC_ORDER_TYPE, WASM_SEC_ORDER_IMPORT}, // WASM_SEC_ORDER_TYPE,
+        {WASM_SEC_ORDER_IMPORT,
+         WASM_SEC_ORDER_FUNCTION}, // WASM_SEC_ORDER_IMPORT,
+        {WASM_SEC_ORDER_FUNCTION,
+         WASM_SEC_ORDER_TABLE}, // WASM_SEC_ORDER_FUNCTION,
+        {WASM_SEC_ORDER_TABLE, WASM_SEC_ORDER_MEMORY}, // WASM_SEC_ORDER_TABLE,
+        {WASM_SEC_ORDER_MEMORY,
+         WASM_SEC_ORDER_GLOBAL},                       // WASM_SEC_ORDER_MEMORY,
+        {WASM_SEC_ORDER_GLOBAL, WASM_SEC_ORDER_EVENT}, // WASM_SEC_ORDER_GLOBAL,
+        {WASM_SEC_ORDER_EVENT, WASM_SEC_ORDER_EXPORT}, // WASM_SEC_ORDER_EVENT,
+        {WASM_SEC_ORDER_EXPORT, WASM_SEC_ORDER_START}, // WASM_SEC_ORDER_EXPORT,
+        {WASM_SEC_ORDER_START, WASM_SEC_ORDER_ELEM},   // WASM_SEC_ORDER_START,
+        {WASM_SEC_ORDER_ELEM, WASM_SEC_ORDER_DATACOUNT}, // WASM_SEC_ORDER_ELEM,
+        {WASM_SEC_ORDER_DATACOUNT,
+         WASM_SEC_ORDER_CODE},                      // WASM_SEC_ORDER_DATACOUNT,
+        {WASM_SEC_ORDER_CODE, WASM_SEC_ORDER_DATA}, // WASM_SEC_ORDER_CODE,
+        {WASM_SEC_ORDER_DATA, WASM_SEC_ORDER_LINKING}, // WASM_SEC_ORDER_DATA,
+
+        // Custom Sections
+        {WASM_SEC_ORDER_DYLINK, WASM_SEC_ORDER_TYPE}, // WASM_SEC_ORDER_DYLINK,
+        {WASM_SEC_ORDER_LINKING, WASM_SEC_ORDER_RELOC,
+         WASM_SEC_ORDER_NAME}, // WASM_SEC_ORDER_LINKING,
+        {},                    // WASM_SEC_ORDER_RELOC (can be repeated),
+        {WASM_SEC_ORDER_NAME, WASM_SEC_ORDER_PRODUCERS}, // WASM_SEC_ORDER_NAME,
+        {WASM_SEC_ORDER_PRODUCERS,
+         WASM_SEC_ORDER_TARGET_FEATURES}, // WASM_SEC_ORDER_PRODUCERS,
+        {WASM_SEC_ORDER_TARGET_FEATURES}  // WASM_SEC_ORDER_TARGET_FEATURES
 };
 
 bool WasmSectionOrderChecker::isValidSectionOrder(unsigned ID,
diff --git a/llvm/lib/ObjectYAML/WasmYAML.cpp b/llvm/lib/ObjectYAML/WasmYAML.cpp
--- a/llvm/lib/ObjectYAML/WasmYAML.cpp
+++ b/llvm/lib/ObjectYAML/WasmYAML.cpp
@@ -81,6 +81,11 @@
   IO.mapOptional("SDKs", Section.SDKs);
 }
 
+static void sectionMapping(IO &IO, WasmYAML::TargetFeaturesSection &Section) {
+  commonSectionMapping(IO, Section);
+  IO.mapRequired("Features", Section.Features);
+}
+
 static void sectionMapping(IO &IO, WasmYAML::CustomSection &Section) {
   commonSectionMapping(IO, Section);
   IO.mapRequired("Name", Section.Name);
@@ -180,6 +185,10 @@
       if (!IO.outputting())
         Section.reset(new WasmYAML::ProducersSection());
       sectionMapping(IO, *cast<WasmYAML::ProducersSection>(Section.get()));
+    } else if (SectionName == "target_features") {
+      if (!IO.outputting())
+        Section.reset(new WasmYAML::TargetFeaturesSection());
+      sectionMapping(IO, *cast<WasmYAML::TargetFeaturesSection>(Section.get()));
     } else {
       if (!IO.outputting())
         Section.reset(new WasmYAML::CustomSection(SectionName));
@@ -310,6 +319,21 @@
   IO.mapRequired("Version", ProducerEntry.Version);
 }
 
+void ScalarEnumerationTraits<WasmYAML::FeaturePolicyPrefix>::enumeration(
+    IO &IO, WasmYAML::FeaturePolicyPrefix &Kind) {
+#define ECase(X) IO.enumCase(Kind, #X, wasm::WASM_FEATURE_PREFIX_##X);
+  ECase(USED);
+  ECase(REQUIRED);
+  ECase(DISALLOWED);
+#undef ECase
+}
+
+void MappingTraits<WasmYAML::FeatureEntry>::mapping(
+    IO &IO, WasmYAML::FeatureEntry &FeatureEntry) {
+  IO.mapRequired("Prefix", FeatureEntry.Prefix);
+  IO.mapRequired("Name", FeatureEntry.Name);
+}
+
 void MappingTraits<WasmYAML::SegmentInfo>::mapping(
     IO &IO, WasmYAML::SegmentInfo &SegmentInfo) {
   IO.mapRequired("Index", SegmentInfo.Index);
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.h b/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.h
--- a/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.h
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.h
@@ -59,6 +59,7 @@
 
   void EmitEndOfAsmFile(Module &M) override;
   void EmitProducerInfo(Module &M);
+  void EmitTargetFeatures();
   void EmitJumpTableInfo() override;
   void EmitConstantPool() override;
   void EmitFunctionBodyStart() override;
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
--- a/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
@@ -21,6 +21,7 @@
 #include "WebAssemblyMCInstLower.h"
 #include "WebAssemblyMachineFunctionInfo.h"
 #include "WebAssemblyRegisterInfo.h"
+#include "WebAssemblyTargetMachine.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/CodeGen/Analysis.h"
@@ -159,6 +160,7 @@
   }
 
   EmitProducerInfo(M);
+  EmitTargetFeatures();
 }
 
 void WebAssemblyAsmPrinter::EmitProducerInfo(Module &M) {
@@ -212,6 +214,65 @@
   }
 }
 
+void WebAssemblyAsmPrinter::EmitTargetFeatures() {
+  static const std::pair<unsigned, const char *> FeaturePairs[] = {
+      {WebAssembly::FeatureAtomics, "atomics"},
+      {WebAssembly::FeatureBulkMemory, "bulk-memory"},
+      {WebAssembly::FeatureExceptionHandling, "exception-handling"},
+      {WebAssembly::FeatureNontrappingFPToInt, "nontrapping-fptoint"},
+      {WebAssembly::FeatureSignExt, "sign-ext"},
+      {WebAssembly::FeatureSIMD128, "simd128"},
+  };
+
+  struct FeatureEntry {
+    enum : uint8_t {
+      Used = '+',
+      Required = '=',
+      Disallowed = '-',
+    } Prefix;
+    StringRef Name;
+  };
+
+  FeatureBitset UsedFeatures =
+      static_cast<WebAssemblyTargetMachine &>(TM).getUsedFeatures();
+
+  // Calculate the features and linkage policies to emit
+  SmallVector<FeatureEntry, 4> EmittedFeatures;
+  for (auto &F : FeaturePairs) {
+    FeatureEntry Entry;
+    Entry.Name = F.second;
+    if (F.first == WebAssembly::FeatureAtomics) {
+      // "atomics" is special: code compiled without atomics may have had its
+      // atomics lowered to nonatomic operations. Such code would be dangerous
+      // to mix with proper atomics, so it is always Required or Disallowed.
+      Entry.Prefix = UsedFeatures[F.first] ? FeatureEntry::Required
+                                           : FeatureEntry::Disallowed;
+      EmittedFeatures.push_back(Entry);
+    } else {
+      // Other features are marked Used or not mentioned
+      if (UsedFeatures[F.first]) {
+        Entry.Prefix = FeatureEntry::Used;
+        EmittedFeatures.push_back(Entry);
+      }
+    }
+  }
+
+  // Emit features and linkage policies into the "target_features" section
+  MCSectionWasm *FeaturesSection = OutContext.getWasmSection(
+      ".custom_section.target_features", SectionKind::getMetadata());
+  OutStreamer->PushSection();
+  OutStreamer->SwitchSection(FeaturesSection);
+
+  OutStreamer->EmitULEB128IntValue(EmittedFeatures.size());
+  for (auto &F : EmittedFeatures) {
+    OutStreamer->EmitIntValue(F.Prefix, 1);
+    OutStreamer->EmitULEB128IntValue(F.Name.size());
+    OutStreamer->EmitBytes(F.Name);
+  }
+
+  OutStreamer->PopSection();
+}
+
 void WebAssemblyAsmPrinter::EmitConstantPool() {
   assert(MF->getConstantPool()->getConstants().empty() &&
          "WebAssembly disables constant pools");
diff --git a/llvm/test/MC/WebAssembly/array-fill.ll b/llvm/test/MC/WebAssembly/array-fill.ll
--- a/llvm/test/MC/WebAssembly/array-fill.ll
+++ b/llvm/test/MC/WebAssembly/array-fill.ll
@@ -24,4 +24,8 @@
 ; CHECK-NEXT:         Name:            .data
 ; CHECK-NEXT:         Alignment:       0
 ; CHECK-NEXT:         Flags:           [ ]
+; CHECK-NEXT:   - Type:            CUSTOM
+; CHECK-NEXT:     Features:
+; CHECK-NEXT:       - Prefix:          DISALLOWED
+; CHECK-NEXT:         Name:            atomics
 ; CHECK-NEXT: ...
diff --git a/llvm/test/MC/WebAssembly/assembler-binary.ll b/llvm/test/MC/WebAssembly/assembler-binary.ll
--- a/llvm/test/MC/WebAssembly/assembler-binary.ll
+++ b/llvm/test/MC/WebAssembly/assembler-binary.ll
@@ -87,4 +87,8 @@
 ; CHECK-NEXT:         Name:            bar
 ; CHECK-NEXT:         Flags:           [ UNDEFINED ]
 ; CHECK-NEXT:         Function:        0
+; CHECK-NEXT:   - Type:            CUSTOM
+; CHECK-NEXT:     Features:
+; CHECK-NEXT:       - Prefix:          DISALLOWED
+; CHECK-NEXT:         Name:            atomics
 ; CHECK-NEXT: ...
diff --git a/llvm/test/MC/WebAssembly/bss.ll b/llvm/test/MC/WebAssembly/bss.ll
--- a/llvm/test/MC/WebAssembly/bss.ll
+++ b/llvm/test/MC/WebAssembly/bss.ll
@@ -78,4 +78,8 @@
 ; CHECK-NEXT:         Name:            .bss.bar
 ; CHECK-NEXT:         Alignment:       0
 ; CHECK-NEXT:         Flags:           [ ]
+; CHECK-NEXT:   - Type:            CUSTOM
+; CHECK-NEXT:     Features:
+; CHECK-NEXT:       - Prefix:          DISALLOWED
+; CHECK-NEXT:         Name:            atomics
 ; CHECK-NEXT: ...
diff --git a/llvm/test/MC/WebAssembly/comdat.ll b/llvm/test/MC/WebAssembly/comdat.ll
--- a/llvm/test/MC/WebAssembly/comdat.ll
+++ b/llvm/test/MC/WebAssembly/comdat.ll
@@ -119,4 +119,8 @@
 ; CHECK-NEXT:            Index:           3
 ; CHECK-NEXT:          - Kind:            DATA
 ; CHECK-NEXT:            Index:           0
+; CHECK-NEXT:   - Type:            CUSTOM
+; CHECK-NEXT:     Features:
+; CHECK-NEXT:       - Prefix:          DISALLOWED
+; CHECK-NEXT:         Name:            atomics
 ; CHECK-NEXT: ...
diff --git a/llvm/test/MC/WebAssembly/debug-info.ll b/llvm/test/MC/WebAssembly/debug-info.ll
--- a/llvm/test/MC/WebAssembly/debug-info.ll
+++ b/llvm/test/MC/WebAssembly/debug-info.ll
@@ -130,6 +130,12 @@
 ; CHECK-NEXT:    Offset: 1021
 ; CHECK-NEXT:    Name: producers
 ; CHECK-NEXT:  }
+; CHECK-NEXT:  Section {
+; CHECK-NEXT:    Type: CUSTOM (0x0)
+; CHECK-NEXT:    Size: 10
+; CHECK-NEXT:    Offset: 1114
+; CHECK-NEXT:    Name: target_features
+; CHECK-NEXT:  }
 ; CHECK-NEXT:]
 ; CHECK-NEXT:Relocations [
 ; CHECK-NEXT:  Section (6) DATA {
diff --git a/llvm/test/MC/WebAssembly/explicit-sections.ll b/llvm/test/MC/WebAssembly/explicit-sections.ll
--- a/llvm/test/MC/WebAssembly/explicit-sections.ll
+++ b/llvm/test/MC/WebAssembly/explicit-sections.ll
@@ -70,4 +70,8 @@
 ; CHECK-NEXT:         Name:            .sec2
 ; CHECK-NEXT:         Alignment:       3
 ; CHECK-NEXT:         Flags:           [ ]
+; CHECK-NEXT:   - Type:            CUSTOM
+; CHECK-NEXT:     Features:
+; CHECK-NEXT:       - Prefix:          DISALLOWED
+; CHECK-NEXT:         Name:            atomics
 ; CHECK-NEXT: ...
diff --git a/llvm/test/MC/WebAssembly/global-ctor-dtor.ll b/llvm/test/MC/WebAssembly/global-ctor-dtor.ll
--- a/llvm/test/MC/WebAssembly/global-ctor-dtor.ll
+++ b/llvm/test/MC/WebAssembly/global-ctor-dtor.ll
@@ -181,4 +181,8 @@
 ; CHECK-NEXT:         Symbol: 10
 ; CHECK-NEXT:       - Priority: 65535
 ; CHECK-NEXT:         Symbol: 7
+; CHECK-NEXT:   - Type:            CUSTOM
+; CHECK-NEXT:     Features:
+; CHECK-NEXT:       - Prefix:          DISALLOWED
+; CHECK-NEXT:         Name:            atomics
 ; CHECK-NEXT: ...
diff --git a/llvm/test/MC/WebAssembly/visibility.ll b/llvm/test/MC/WebAssembly/visibility.ll
--- a/llvm/test/MC/WebAssembly/visibility.ll
+++ b/llvm/test/MC/WebAssembly/visibility.ll
@@ -25,4 +25,8 @@
 ; CHECK-NEXT:         Name:            hiddenVis
 ; CHECK-NEXT:         Flags:           [ VISIBILITY_HIDDEN ]
 ; CHECK-NEXT:         Function:        1
+; CHECK-NEXT:   - Type:            CUSTOM
+; CHECK-NEXT:     Features:
+; CHECK-NEXT:       - Prefix:          DISALLOWED
+; CHECK-NEXT:         Name:            atomics
 ; CHECK-NEXT: ...
diff --git a/llvm/test/MC/WebAssembly/weak-alias.ll b/llvm/test/MC/WebAssembly/weak-alias.ll
--- a/llvm/test/MC/WebAssembly/weak-alias.ll
+++ b/llvm/test/MC/WebAssembly/weak-alias.ll
@@ -207,6 +207,10 @@
 ; CHECK-NEXT:         Name:            .data.alias_address
 ; CHECK-NEXT:         Alignment:       3
 ; CHECK-NEXT:         Flags:           [ ]
+; CHECK-NEXT:   - Type:            CUSTOM
+; CHECK-NEXT:     Features:
+; CHECK-NEXT:       - Prefix:          DISALLOWED
+; CHECK-NEXT:         Name:            atomics
 ; CHECK-NEXT: ...
 
 ; CHECK-SYMS: SYMBOL TABLE:
diff --git a/llvm/test/MC/WebAssembly/weak.ll b/llvm/test/MC/WebAssembly/weak.ll
--- a/llvm/test/MC/WebAssembly/weak.ll
+++ b/llvm/test/MC/WebAssembly/weak.ll
@@ -30,4 +30,8 @@
 ; CHECK-NEXT:         Kind:            DATA
 ; CHECK-NEXT:         Name:            weak_external_data
 ; CHECK-NEXT:         Flags:           [ BINDING_WEAK, UNDEFINED ]
+; CHECK-NEXT:   - Type:            CUSTOM
+; CHECK-NEXT:     Features:
+; CHECK-NEXT:       - Prefix:          DISALLOWED
+; CHECK-NEXT:         Name:            atomics
 ; CHECK-NEXT: ...
diff --git a/llvm/tools/obj2yaml/wasm2yaml.cpp b/llvm/tools/obj2yaml/wasm2yaml.cpp
--- a/llvm/tools/obj2yaml/wasm2yaml.cpp
+++ b/llvm/tools/obj2yaml/wasm2yaml.cpp
@@ -155,6 +155,16 @@
       ProducersSec->SDKs.push_back(Producer);
     }
     CustomSec = std::move(ProducersSec);
+  } else if (WasmSec.Name == "target_features") {
+    std::unique_ptr<WasmYAML::TargetFeaturesSection> TargetFeaturesSec =
+        make_unique<WasmYAML::TargetFeaturesSection>();
+    for (auto &E : Obj.getTargetFeatures()) {
+      WasmYAML::FeatureEntry Feature;
+      Feature.Prefix = E.Prefix;
+      Feature.Name = E.Name;
+      TargetFeaturesSec->Features.push_back(Feature);
+    }
+    CustomSec = std::move(TargetFeaturesSec);
   } else {
     CustomSec = make_unique<WasmYAML::CustomSection>(WasmSec.Name);
   }
diff --git a/llvm/tools/yaml2obj/yaml2wasm.cpp b/llvm/tools/yaml2obj/yaml2wasm.cpp
--- a/llvm/tools/yaml2obj/yaml2wasm.cpp
+++ b/llvm/tools/yaml2obj/yaml2wasm.cpp
@@ -49,6 +49,8 @@
   int writeSectionContent(raw_ostream &OS, WasmYAML::NameSection &Section);
   int writeSectionContent(raw_ostream &OS, WasmYAML::LinkingSection &Section);
   int writeSectionContent(raw_ostream &OS, WasmYAML::ProducersSection &Section);
+  int writeSectionContent(raw_ostream &OS,
+                          WasmYAML::TargetFeaturesSection &Section);
   WasmYAML::Object &Obj;
   uint32_t NumImportedFunctions = 0;
   uint32_t NumImportedGlobals = 0;
@@ -279,6 +281,18 @@
   return 0;
 }
 
+int WasmWriter::writeSectionContent(raw_ostream &OS,
+                                    WasmYAML::TargetFeaturesSection &Section) {
+  writeStringRef(Section.Name, OS);
+  encodeULEB128(Section.Features.size(), OS);
+  for (auto &E : Section.Features) {
+    writeUint8(OS, E.Prefix);
+    encodeULEB128(E.Name.size(), OS);
+    writeStringRef(E.Name, OS);
+  }
+  return 0;
+}
+
 int WasmWriter::writeSectionContent(raw_ostream &OS,
                                     WasmYAML::CustomSection &Section) {
   if (auto S = dyn_cast<WasmYAML::DylinkSection>(&Section)) {