Index: test/wasm/demangle.ll
===================================================================
--- test/wasm/demangle.ll
+++ test/wasm/demangle.ll
@@ -1,17 +1,19 @@
 ; RUN: llc -filetype=obj %s -o %t.o
-; RUN: not wasm-ld --undefined _Z3fooi \
-; RUN:     -o %t.wasm %t.o 2>&1 | FileCheck %s
+; RUN: not wasm-ld -o %t.wasm %t.o 2>&1 | FileCheck %s
 
-; CHECK: error: undefined symbol: foo(int)
+; CHECK: error: {{.*}}.o: undefined symbol: foo(int)
 
-; RUN: not wasm-ld --no-demangle --undefined _Z3fooi \
-; RUN:     -o %t.wasm %t.o 2>&1 |  FileCheck -check-prefix=CHECK-NODEMANGLE %s
+; RUN: not wasm-ld --no-demangle \
+; RUN:     -o %t.wasm %t.o 2>&1 | FileCheck -check-prefix=CHECK-NODEMANGLE %s
 
-; CHECK-NODEMANGLE: error: undefined symbol: _Z3fooi
+; CHECK-NODEMANGLE: error: {{.*}}.o: undefined symbol: _Z3fooi
 
 target triple = "wasm32-unknown-unknown"
 
+declare void @_Z3fooi(i32);
+
 define hidden void @_start() local_unnamed_addr {
 entry:
+    call void @_Z3fooi(i32 1)
     ret void
 }
Index: test/wasm/load-undefined.test
===================================================================
--- test/wasm/load-undefined.test
+++ test/wasm/load-undefined.test
@@ -33,9 +33,6 @@
 ; NO-LOAD-NEXT:        Name:            ret64
 ; NO-LOAD-NEXT: ...
 
-; Verify that referencing a symbol that doesn't exist won't work
-; RUN: not wasm-ld %t.start.o -o %t.wasm -u symboldoesnotexist 2>&1 | FileCheck -check-prefix=CHECK-UNDEFINED1 %s
-; CHECK-UNDEFINED1: error: undefined symbol: symboldoesnotexist
-
-; RUN: not wasm-ld %t.start.o -o %t.wasm --undefined symboldoesnotexist --allow-undefined 2>&1 | FileCheck -check-prefix=CHECK-UNDEFINED2 %s
-; CHECK-UNDEFINED2: symbol forced with --undefined not found: symboldoesnotexist
+; Verify that referencing a symbol that is not found doesn't result in a link
+; failure.  This matches the behaviour of the ELF linker.
+; RUN: wasm-ld %t.start.o -o %t.wasm -u symboldoesnotexist
Index: test/wasm/undefined-entry.test
===================================================================
--- test/wasm/undefined-entry.test
+++ test/wasm/undefined-entry.test
@@ -1,11 +1,9 @@
 RUN: llc -filetype=obj %p/Inputs/ret32.ll -o %t.ret32.o
 RUN: not wasm-ld -o %t.wasm %t.ret32.o 2>&1 | FileCheck %s
+RUN: not wasm-ld --allow-undefined -o %t.wasm %t.ret32.o 2>&1 | FileCheck %s
 RUN: not wasm-ld -entry=foo -o %t.wasm %t.ret32.o 2>&1 | FileCheck %s -check-prefix=CHECK-CUSTOM
-RUN: not wasm-ld --allow-undefined -o %t.wasm %t.ret32.o 2>&1 | FileCheck %s -check-prefix=CHECK-ALLOW
 
-CHECK: error: undefined symbol: _start
-CHECK-CUSTOM: error: undefined symbol: foo
-CHECK-ALLOW: error: entry symbol not defined (pass --no-entry to supress):
-_start
+CHECK: error: entry symbol not defined (pass --no-entry to supress): _start
+CHECK-CUSTOM: error: entry symbol not defined (pass --no-entry to supress): foo
 
 RUN: wasm-ld --no-entry -o %t.wasm %t.ret32.o
Index: test/wasm/undefined.ll
===================================================================
--- test/wasm/undefined.ll
+++ test/wasm/undefined.ll
@@ -1,10 +1,10 @@
 ; RUN: llc -filetype=obj %s -o %t.o
 ; RUN: wasm-ld --allow-undefined -o %t.wasm %t.o
 
-; Fails due to undefined 'foo' and also 'baz'
+; Fails due to undefined 'foo' 
 ; RUN: not wasm-ld --undefined=baz -o %t.wasm %t.o 2>&1 | FileCheck %s
 ; CHECK: error: {{.*}}.o: undefined symbol: foo
-; CHECK: error: undefined symbol: baz
+; CHECK-NOT: undefined symbol: baz
 
 ; Succeeds if we pass a file containing 'foo' as --allow-undefined-file.
 ; RUN: echo 'foo' > %t.txt
Index: wasm/Driver.cpp
===================================================================
--- wasm/Driver.cpp
+++ wasm/Driver.cpp
@@ -505,23 +505,16 @@
     return;
 
   // Make sure we have resolved all symbols.
-  if (!Config->Relocatable && !Config->AllowUndefined) {
+  if (!Config->Relocatable && !Config->AllowUndefined)
     Symtab->reportRemainingUndefines();
-  } else {
-    // Even when using --allow-undefined we still want to report the absence of
-    // our initial set of undefined symbols (i.e. the entry point and symbols
-    // specified via --undefined).
-    // Part of the reason for this is that these function don't have signatures
-    // so which means they cannot be written as wasm function imports.
-    for (auto *Arg : Args.filtered(OPT_undefined)) {
-      Symbol *Sym = Symtab->find(Arg->getValue());
-      if (!Sym->isDefined())
-        error("symbol forced with --undefined not found: " + Sym->getName());
-    }
-    if (EntrySym && !EntrySym->isDefined())
-      error("entry symbol not defined (pass --no-entry to supress): " +
-            EntrySym->getName());
-  }
+
+  // Handle entry point specially since reportRemainingUndefines() won't
+  // report errors for symbols that don't come from files (e.g. --undefined or
+  // the entry symbol).
+  if (EntrySym && !EntrySym->isDefined())
+    error("entry symbol not defined (pass --no-entry to supress): " +
+          EntrySym->getName());
+
   if (errorCount())
     return;
 
Index: wasm/SymbolTable.cpp
===================================================================
--- wasm/SymbolTable.cpp
+++ wasm/SymbolTable.cpp
@@ -60,7 +60,6 @@
 }
 
 void SymbolTable::reportRemainingUndefines() {
-  SetVector<Symbol *> Undefs;
   for (Symbol *Sym : SymVector) {
     if (!Sym->isUndefined() || Sym->isWeak())
       continue;
@@ -68,20 +67,12 @@
       continue;
     if (!Sym->IsUsedInRegularObj)
       continue;
-    Undefs.insert(Sym);
-  }
-
-  if (Undefs.empty())
-    return;
-
-  for (ObjFile *File : ObjectFiles)
-    for (Symbol *Sym : File->getSymbols())
-      if (Undefs.count(Sym))
-        error(toString(File) + ": undefined symbol: " + toString(*Sym));
-
-  for (Symbol *Sym : Undefs)
+    // Don't report undefined symbols that came from --undefined flag
+    // rather than from an actual file.
     if (!Sym->getFile())
-      error("undefined symbol: " + toString(*Sym));
+      continue;
+    error(toString(Sym->getFile()) + ": undefined symbol: " + toString(*Sym));
+  }
 }
 
 Symbol *SymbolTable::find(StringRef Name) {
Index: wasm/Writer.cpp
===================================================================
--- wasm/Writer.cpp
+++ wasm/Writer.cpp
@@ -845,8 +845,10 @@
   }
 
   for (const Symbol *Sym : ImportedSymbols)
-    if (auto *F = dyn_cast<FunctionSymbol>(Sym))
+    if (auto *F = dyn_cast<FunctionSymbol>(Sym)) {
+      assert(F->FunctionType != nullptr);
       registerType(*F->FunctionType);
+    }
 
   for (const InputFunction *F : InputFunctions)
     registerType(F->Signature);