Index: lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
===================================================================
--- lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
+++ lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
@@ -225,13 +225,8 @@
 
 namespace {
 class WebAssemblyLowerEmscriptenEHSjLj final : public ModulePass {
-  static const char *ThrewGVName;
-  static const char *ThrewValueGVName;
-  static const char *TempRet0GVName;
   static const char *ResumeFName;
   static const char *EHTypeIDFName;
-  static const char *SetThrewFName;
-  static const char *SetTempRet0FName;
   static const char *EmLongjmpFName;
   static const char *EmLongjmpJmpbufFName;
   static const char *SaveSetjmpFName;
@@ -300,14 +295,9 @@
 };
 } // End anonymous namespace
 
-const char *WebAssemblyLowerEmscriptenEHSjLj::ThrewGVName = "__THREW__";
-const char *WebAssemblyLowerEmscriptenEHSjLj::ThrewValueGVName = "__threwValue";
-const char *WebAssemblyLowerEmscriptenEHSjLj::TempRet0GVName = "__tempRet0";
 const char *WebAssemblyLowerEmscriptenEHSjLj::ResumeFName = "__resumeException";
 const char *WebAssemblyLowerEmscriptenEHSjLj::EHTypeIDFName =
     "llvm_eh_typeid_for";
-const char *WebAssemblyLowerEmscriptenEHSjLj::SetThrewFName = "setThrew";
-const char *WebAssemblyLowerEmscriptenEHSjLj::SetTempRet0FName = "setTempRet0";
 const char *WebAssemblyLowerEmscriptenEHSjLj::EmLongjmpFName =
     "emscripten_longjmp";
 const char *WebAssemblyLowerEmscriptenEHSjLj::EmLongjmpJmpbufFName =
@@ -343,17 +333,6 @@
   return true;
 }
 
-// Returns an available name for a global value.
-// If the proposed name already exists in the module, adds '_' at the end of
-// the name until the name is available.
-static inline std::string createGlobalValueName(const Module &M,
-                                                const std::string &Propose) {
-  std::string Name = Propose;
-  while (M.getNamedGlobal(Name))
-    Name += "_";
-  return Name;
-}
-
 // Simple function name mangler.
 // This function simply takes LLVM's string representation of parameter types
 // and concatenate them with '_'. There are non-alphanumeric characters but llc
@@ -613,11 +592,13 @@
   LLVMContext &C = M.getContext();
   IRBuilder<> IRB(C);
 
-  assert(!M.getNamedGlobal(SetThrewFName) && "setThrew already exists");
+  if (M.getNamedGlobal("setThrew"))
+    report_fatal_error("setThrew already exists");
+
   Type *Params[] = {IRB.getInt32Ty(), IRB.getInt32Ty()};
   FunctionType *FTy = FunctionType::get(IRB.getVoidTy(), Params, false);
   Function *F =
-      Function::Create(FTy, GlobalValue::ExternalLinkage, SetThrewFName, &M);
+      Function::Create(FTy, GlobalValue::WeakODRLinkage, "setThrew", &M);
   Argument *Arg1 = &*(F->arg_begin());
   Argument *Arg2 = &*std::next(F->arg_begin());
   Arg1->setName("threw");
@@ -648,11 +629,12 @@
   LLVMContext &C = M.getContext();
   IRBuilder<> IRB(C);
 
-  assert(!M.getNamedGlobal(SetTempRet0FName) && "setTempRet0 already exists");
+  if (M.getNamedGlobal("setTempRet0"))
+    report_fatal_error("setTempRet0 already exists");
   Type *Params[] = {IRB.getInt32Ty()};
   FunctionType *FTy = FunctionType::get(IRB.getVoidTy(), Params, false);
   Function *F =
-      Function::Create(FTy, GlobalValue::ExternalLinkage, SetTempRet0FName, &M);
+      Function::Create(FTy, GlobalValue::WeakODRLinkage, "setTempRet0", &M);
   F->arg_begin()->setName("value");
   BasicBlock *EntryBB = BasicBlock::Create(C, "entry", F);
   IRB.SetInsertPoint(EntryBB);
@@ -687,6 +669,15 @@
   }
 }
 
+static GlobalVariable *createGlobalVariable(Module &M, IRBuilder<> &IRB,
+                                            const char *Name) {
+  if (M.getNamedGlobal(Name))
+    report_fatal_error(Twine("variable name is reserved: ") + Name);
+
+  return new GlobalVariable(M, IRB.getInt32Ty(), false,
+                            GlobalValue::WeakODRLinkage, IRB.getInt32(0), Name);
+}
+
 bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) {
   LLVMContext &C = M.getContext();
   IRBuilder<> IRB(C);
@@ -699,15 +690,9 @@
 
   // Create global variables __THREW__, threwValue, and __tempRet0, which are
   // used in common for both exception handling and setjmp/longjmp handling
-  ThrewGV = new GlobalVariable(M, IRB.getInt32Ty(), false,
-                               GlobalValue::ExternalLinkage, IRB.getInt32(0),
-                               createGlobalValueName(M, ThrewGVName));
-  ThrewValueGV = new GlobalVariable(
-      M, IRB.getInt32Ty(), false, GlobalValue::ExternalLinkage, IRB.getInt32(0),
-      createGlobalValueName(M, ThrewValueGVName));
-  TempRet0GV = new GlobalVariable(M, IRB.getInt32Ty(), false,
-                                  GlobalValue::ExternalLinkage, IRB.getInt32(0),
-                                  createGlobalValueName(M, TempRet0GVName));
+  ThrewGV = createGlobalVariable(M, IRB, "__THREW__");
+  ThrewValueGV = createGlobalVariable(M, IRB, "__threwValue");
+  TempRet0GV = createGlobalVariable(M, IRB, "__tempRet0");
 
   bool Changed = false;
 
@@ -736,12 +721,6 @@
   if (DoSjLj) {
     Changed = true; // We have setjmp or longjmp somewhere
 
-    Function *MallocF = M.getFunction("malloc");
-    Function *FreeF = M.getFunction("free");
-    if (!MallocF || !FreeF)
-      report_fatal_error(
-          "malloc and free must be linked into the module if setjmp is used");
-
     // Register saveSetjmp function
     FunctionType *SetjmpFTy = SetjmpF->getFunctionType();
     SmallVector<Type *, 4> Params = {SetjmpFTy->getParamType(0),
Index: test/CodeGen/WebAssembly/lower-em-exceptions.ll
===================================================================
--- test/CodeGen/WebAssembly/lower-em-exceptions.ll
+++ test/CodeGen/WebAssembly/lower-em-exceptions.ll
@@ -5,9 +5,9 @@
 
 @_ZTIi = external constant i8*
 @_ZTIc = external constant i8*
-; CHECK-DAG: @[[__THREW__:__THREW__.*]] = global i32 0
-; CHECK-DAG: @[[THREWVALUE:__threwValue.*]] = global i32 0
-; CHECK-DAG: @[[TEMPRET0:__tempRet0.*]] = global i32 0
+; CHECK-DAG: @[[__THREW__:__THREW__.*]] = weak_odr global i32 0
+; CHECK-DAG: @[[THREWVALUE:__threwValue.*]] = weak_odr global i32 0
+; CHECK-DAG: @[[TEMPRET0:__tempRet0.*]] = weak_odr global i32 0
 
 ; Test invoke instruction with clauses (try-catch block)
 define void @clause() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
@@ -173,7 +173,7 @@
 ; CHECK-DAG: declare i8* @__cxa_find_matching_catch_4(i8*, i8*)
 
 ; setThrew function creation
-; CHECK-LABEL: define void @setThrew(i32 %threw, i32 %value) {
+; CHECK-LABEL: define weak_odr void @setThrew(i32 %threw, i32 %value) {
 ; CHECK: entry:
 ; CHECK-NEXT: %[[__THREW__]].val = load i32, i32* @[[__THREW__]]
 ; CHECK-NEXT: %cmp = icmp eq i32 %[[__THREW__]].val, 0
@@ -187,7 +187,7 @@
 ; CHECK: }
 
 ; setTempRet0 function creation
-; CHECK-LABEL: define void @setTempRet0(i32 %value) {
+; CHECK-LABEL: define weak_odr void @setTempRet0(i32 %value) {
 ; CHECK: entry:
 ; CHECK-NEXT: store i32 %value, i32* @[[TEMPRET0]]
 ; CHECK-NEXT: ret void
Index: test/CodeGen/WebAssembly/lower-em-sjlj.ll
===================================================================
--- test/CodeGen/WebAssembly/lower-em-sjlj.ll
+++ test/CodeGen/WebAssembly/lower-em-sjlj.ll
@@ -6,9 +6,9 @@
 %struct.__jmp_buf_tag = type { [6 x i32], i32, [32 x i32] }
 
 @global_var = hidden global i32 0, align 4
-; CHECK-DAG: @[[__THREW__:__THREW__.*]] = global i32 0
-; CHECK-DAG: @[[THREWVALUE:__threwValue.*]] = global i32 0
-; CHECK-DAG: @[[TEMPRET0:__tempRet0.*]] = global i32 0
+; CHECK-DAG: @[[__THREW__:__THREW__.*]] = weak_odr global i32 0
+; CHECK-DAG: @[[THREWVALUE:__threwValue.*]] = weak_odr global i32 0
+; CHECK-DAG: @[[TEMPRET0:__tempRet0.*]] = weak_odr global i32 0
 
 ; Test a simple setjmp - longjmp sequence
 define hidden void @setjmp_longjmp() {