Index: include/llvm/Object/Wasm.h
===================================================================
--- include/llvm/Object/Wasm.h
+++ include/llvm/Object/Wasm.h
@@ -204,6 +204,8 @@
   bool isValidGlobalIndex(uint32_t Index) const;
   bool isDefinedGlobalIndex(uint32_t Index) const;
   bool isValidFunctionSymbolIndex(uint32_t Index) const;
+  bool isValidGlobalSymbolIndex(uint32_t Index) const;
+  bool isValidDataSymbolIndex(uint32_t Index) const;
   wasm::WasmFunction &getDefinedFunction(uint32_t Index);
   wasm::WasmGlobal &getDefinedGlobal(uint32_t Index);
 
@@ -238,6 +240,7 @@
   Error parseLinkingSectionComdat(const uint8_t *&Ptr, const uint8_t *End);
   Error parseRelocSection(StringRef Name, const uint8_t *Ptr,
                           const uint8_t *End);
+  Error validateRelocSection();
 
   wasm::WasmObjectHeader Header;
   std::vector<WasmSection> Sections;
Index: lib/Object/WasmObjectFile.cpp
===================================================================
--- lib/Object/WasmObjectFile.cpp
+++ lib/Object/WasmObjectFile.cpp
@@ -232,6 +232,9 @@
 
     Sections.push_back(Sec);
   }
+
+  if ((Err = validateRelocSection()))
+    return;
 }
 
 Error WasmObjectFile::parseSection(WasmSection &Sec) {
@@ -565,9 +568,9 @@
     return make_error<GenericBinaryError>("Invalid section code",
                                           object_error::parse_failed);
   uint32_t RelocCount = readVaruint32(Ptr);
+  uint64_t StartOffset = 0, EndOffset = Section->Content.size();
   while (RelocCount--) {
-    wasm::WasmRelocation Reloc;
-    memset(&Reloc, 0, sizeof(Reloc));
+    wasm::WasmRelocation Reloc = {};
     Reloc.Type = readVaruint32(Ptr);
     Reloc.Offset = readVaruint32(Ptr);
     Reloc.Index = readVaruint32(Ptr);
@@ -588,6 +591,19 @@
                                                 Twine(Reloc.Type),
                                             object_error::parse_failed);
     }
+
+    // Relocations must fit inside the section, and must appear in order.  They
+    // also shouldn't overlap a function/element boundary, but we don't bother
+    // to check that.
+    uint64_t Size = 5;
+    if (Reloc.Type == wasm::R_WEBASSEMBLY_TABLE_INDEX_I32 ||
+        Reloc.Type == wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32)
+      Size = 4;
+    if (Reloc.Offset < StartOffset || Reloc.Offset + Size > EndOffset)
+      return make_error<GenericBinaryError>("Bad relocation offset",
+                                            object_error::parse_failed);
+    StartOffset = Reloc.Offset;
+
     Section->Relocations.push_back(Reloc);
   }
   if (Ptr != End)
@@ -596,6 +612,40 @@
   return Error::success();
 }
 
+Error WasmObjectFile::validateRelocSection() {
+  for (const WasmSection &Section : Sections) {
+    for (const wasm::WasmRelocation &Reloc : Section.Relocations) {
+      switch (Reloc.Type) {
+      case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
+      case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
+      case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
+        if (!isValidFunctionSymbolIndex(Reloc.Index))
+          return make_error<GenericBinaryError>("Bad relocation function index",
+                                                object_error::parse_failed);
+        break;
+      case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
+        if (!isValidGlobalSymbolIndex(Reloc.Index))
+          return make_error<GenericBinaryError>("Bad relocation global index",
+                                                object_error::parse_failed);
+        break;
+      case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB:
+      case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
+      case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
+        if (!isValidDataSymbolIndex(Reloc.Index))
+          return make_error<GenericBinaryError>("Bad relocation data index",
+                                                object_error::parse_failed);
+        break;
+      case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
+        if (Reloc.Index >= Signatures.size())
+          return make_error<GenericBinaryError>("Bad relocation type index",
+                                                object_error::parse_failed);
+        break;
+      }
+    }
+  }
+  return Error::success();
+}
+
 Error WasmObjectFile::parseCustomSection(WasmSection &Sec,
                                          const uint8_t *Ptr, const uint8_t *End) {
   Sec.Name = readString(Ptr);
@@ -797,6 +847,14 @@
   return Index < Symbols.size() && Symbols[Index].isTypeFunction();
 }
 
+bool WasmObjectFile::isValidGlobalSymbolIndex(uint32_t Index) const {
+  return Index < Symbols.size() && Symbols[Index].isTypeGlobal();
+}
+
+bool WasmObjectFile::isValidDataSymbolIndex(uint32_t Index) const {
+  return Index < Symbols.size() && Symbols[Index].isTypeData();
+}
+
 wasm::WasmFunction &WasmObjectFile::getDefinedFunction(uint32_t Index) {
   assert(isDefinedFunctionIndex(Index));
   return Functions[Index - NumImportedFunctions];
Index: test/ObjectYAML/wasm/code_section.yaml
===================================================================
--- test/ObjectYAML/wasm/code_section.yaml
+++ test/ObjectYAML/wasm/code_section.yaml
@@ -37,6 +37,20 @@
          - Type:            I32
            Count:           1
         Body:            108180808000210020000F0B
+  - Type:            CUSTOM
+    Name:            linking
+    DataSize:        0
+    SymbolTable:
+      - Index:           0
+        Kind:            FUNCTION
+        Name:            func1
+        Flags:           [  ]
+        Function:        0
+      - Index:           1
+        Kind:            FUNCTION
+        Name:            func2
+        Flags:           [  ]
+        Function:        1
 ...
 # CHECK: --- !WASM
 # CHECK: FileHeader:
Index: test/ObjectYAML/wasm/data_section.yaml
===================================================================
--- test/ObjectYAML/wasm/data_section.yaml
+++ test/ObjectYAML/wasm/data_section.yaml
@@ -22,6 +22,17 @@
         Index:           0
         Offset:          0x00000006
         Addend:          -6
+  - Type:            CUSTOM
+    Name:            linking
+    DataSize:        4
+    SymbolTable:
+      - Index:           0
+        Kind:            DATA
+        Name:            dataSymbol
+        Flags:           [  ]
+        Segment:         0
+        Offset:          0
+        Size:            4
 ...
 # CHECK: --- !WASM
 # CHECK: FileHeader:
@@ -44,4 +55,4 @@
 # CHECK-NEXT:           Opcode:          I32_CONST
 # CHECK-NEXT:           Value:           4
 # CHECK-NEXT:         Content:         '10001000'
-# CHECK-NEXT: ...
+# CHECK-NEXT:   - Type:            CUSTOM