diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
--- a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
@@ -932,6 +932,18 @@
     }
   }
 
+  // Above, we registered emscripten_longjmp function only when it SjLj is
+  // actually used. But there is a case we need emscripten_longjmp when we
+  // rethrow longjmps after checking for an Emscripten exception. Refer to
+  // runEHOnFunction for details.
+  if (EnableEmEH && EnableEmSjLj && !EmLongjmpF) {
+    // Register emscripten_longjmp function
+    FunctionType *FTy = FunctionType::get(
+        IRB.getVoidTy(), {getAddrIntType(&M), IRB.getInt32Ty()}, false);
+    EmLongjmpF = getEmscriptenFunction(FTy, "emscripten_longjmp", &M);
+    EmLongjmpF->addFnAttr(Attribute::NoReturn);
+  }
+
   // Exception handling transformation
   if (EnableEmEH) {
     for (Function &F : M) {
@@ -1009,6 +1021,11 @@
       // value is 0 when nothing happened, 1 when an exception is thrown, and
       // other values when longjmp is thrown.
       //
+      // Note that we do this whenever -enable-emscripten-sjlj is on, regardless
+      // of whether there is actual usage of setjmp/longjmp within the module.
+      // Because we use wasm-ld to link files, what we see here is not the whole
+      // program, and there can be a longjmp call in another file.
+      //
       // if (%__THREW__.val == 0 || %__THREW__.val == 1)
       //   goto %tail
       // else
@@ -1020,8 +1037,7 @@
       //
       // tail: ;; Nothing happened or an exception is thrown
       //   ... Continue exception handling ...
-      if (DoSjLj && EnableEmSjLj && !SetjmpUsers.count(&F) &&
-          canLongjmp(Callee)) {
+      if (EnableEmSjLj && !SetjmpUsers.count(&F) && canLongjmp(Callee)) {
         // Create longjmp.rethrow BB once and share it within the function
         if (!RethrowLongjmpBB) {
           RethrowLongjmpBB = BasicBlock::Create(C, "rethrow.longjmp", &F);
diff --git a/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-sjlj-not-used.ll b/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-sjlj-not-used.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-sjlj-not-used.ll
@@ -0,0 +1,59 @@
+; RUN: opt < %s -wasm-lower-em-ehsjlj -enable-emscripten-cxx-exceptions -enable-emscripten-sjlj -S | FileCheck %s
+; RUN: llc < %s -enable-emscripten-cxx-exceptions -enable-emscripten-sjlj -verify-machineinstrs
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+; The same test with the same function in lower-em-ehsjlj.ll, both the
+; Emscripten EH and Emscripten SjLj are enabled in the same way, and this
+; function only does exception handling. The difference is that this module does
+; not contain any calls to setjmp or longjmp.
+;
+; But we still have to check if the thrown value is longjmp and and if so
+; rethrow it by calling @emscripten_longjmp, because we link object files using
+; wasm-ld, so the module we see in LowerEmscriptenEHSjLj pass is not the whole
+; program and there can be a longjmp call within another file.
+define void @rethrow_longjmp() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
+; CHECK-LABEL: @rethrow_longjmp
+entry:
+  invoke void @foo()
+          to label %try.cont unwind label %lpad
+; CHECK:    entry:
+; CHECK:      %cmp.eq.one = icmp eq i32 %__THREW__.val, 1
+; CHECK-NEXT: %cmp.eq.zero = icmp eq i32 %__THREW__.val, 0
+; CHECK-NEXT: %or = or i1 %cmp.eq.zero, %cmp.eq.one
+; CHECK-NEXT: br i1 %or, label %tail, label %rethrow.longjmp
+
+; CHECK: try.cont:
+; CHECK-NEXT:  %phi = phi i32 [ undef, %tail ], [ undef, %lpad ]
+; CHECK-NEXT:  ret void
+
+; CHECK:    rethrow.longjmp:
+; CHECK-NEXT: %threw.phi = phi i32 [ %__THREW__.val, %entry ]
+; CHECK-NEXT: %__threwValue.val = load i32, i32* @__threwValue, align 4
+; CHECK-NEXT: call void @emscripten_longjmp(i32 %threw.phi, i32 %__threwValue.val
+; CHECK-NEXT: unreachable
+
+; CHECK:    tail:
+; CHECK-NEXT: %cmp = icmp eq i32 %__THREW__.val, 1
+; CHECK-NEXT: br i1 %cmp, label %lpad, label %try.cont
+
+lpad:                                             ; preds = %entry
+  %0 = landingpad { i8*, i32 }
+          catch i8* null
+  %1 = extractvalue { i8*, i32 } %0, 0
+  %2 = extractvalue { i8*, i32 } %0, 1
+  %3 = call i8* @__cxa_begin_catch(i8* %1) #5
+  call void @__cxa_end_catch()
+  br label %try.cont
+
+try.cont:                                         ; preds = %lpad, %entry
+ %phi = phi i32 [ undef, %entry ], [ undef, %lpad ]
+  ret void
+}
+
+declare void @foo()
+declare i32 @__gxx_personality_v0(...)
+declare i8* @__cxa_begin_catch(i8*)
+declare void @__cxa_end_catch()
+declare void @__cxa_throw(i8*, i8*, i8*)