diff --git a/src/passes/RemoveNonJSOps.cpp b/src/passes/RemoveNonJSOps.cpp
index 290eec7c8e5..7c7d9d41982 100644
--- a/src/passes/RemoveNonJSOps.cpp
+++ b/src/passes/RemoveNonJSOps.cpp
@@ -356,9 +356,20 @@ struct StubUnsupportedJSOpsPass
 
   void visitUnary(Unary* curr) {
     switch (curr->op) {
+      case ConvertSInt64ToFloat32:
       case ConvertUInt64ToFloat32:
-        // See detailed comment in lowerConvertIntToFloat in
-        // I64ToI32Lowering.cpp.
+      case TruncSatSFloat32ToInt32:
+      case TruncSatUFloat32ToInt32:
+      case TruncSatSFloat64ToInt32:
+      case TruncSatUFloat64ToInt32:
+      case TruncSatSFloat32ToInt64:
+      case TruncSatUFloat32ToInt64:
+      case TruncSatSFloat64ToInt64:
+      case TruncSatUFloat64ToInt64:
+        // f32.convert_i64_s and f32.convert_i64_u do not have perfect rounding
+        // in all cases (see lowerConvertIntToFloat in I64ToI32Lowering.cpp),
+        // and trunc_sat operations are lowered using non-saturating conversions
+        // in wasm2js and I64ToI32Lowering.
         stubOut(curr->value, curr->type);
         break;
       default: {
diff --git a/test/lit/passes/stub-unsupported-js.wast b/test/lit/passes/stub-unsupported-js.wast
new file mode 100644
index 00000000000..71376900bfe
--- /dev/null
+++ b/test/lit/passes/stub-unsupported-js.wast
@@ -0,0 +1,139 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
+
+;; RUN: wasm-opt %s -all --stub-unsupported-js -S -o - | filecheck %s
+
+(module
+ ;; CHECK:      (func $convert_s_i64_f32 (type $1) (param $x i64) (result f32)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (f32.const 0)
+ ;; CHECK-NEXT: )
+ (func $convert_s_i64_f32 (param $x i64) (result f32)
+  ;; Signed and unsigned i64 to f32 conversions are stubbed out.
+  (f32.convert_i64_s
+   (local.get $x)
+  )
+ )
+
+ ;; CHECK:      (func $convert_u_i64_f32 (type $1) (param $x i64) (result f32)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (f32.const 0)
+ ;; CHECK-NEXT: )
+ (func $convert_u_i64_f32 (param $x i64) (result f32)
+  (f32.convert_i64_u
+   (local.get $x)
+  )
+ )
+
+ ;; CHECK:      (func $trunc_sat_s_f32_i32 (type $0) (param $x f32) (result i32)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i32.const 0)
+ ;; CHECK-NEXT: )
+ (func $trunc_sat_s_f32_i32 (param $x f32) (result i32)
+  ;; Nontrapping float-to-int conversions are stubbed out.
+  (i32.trunc_sat_f32_s
+   (local.get $x)
+  )
+ )
+
+ ;; CHECK:      (func $trunc_sat_u_f32_i32 (type $0) (param $x f32) (result i32)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i32.const 0)
+ ;; CHECK-NEXT: )
+ (func $trunc_sat_u_f32_i32 (param $x f32) (result i32)
+  (i32.trunc_sat_f32_u
+   (local.get $x)
+  )
+ )
+
+ ;; CHECK:      (func $trunc_sat_s_f64_i32 (type $2) (param $x f64) (result i32)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i32.const 0)
+ ;; CHECK-NEXT: )
+ (func $trunc_sat_s_f64_i32 (param $x f64) (result i32)
+  (i32.trunc_sat_f64_s
+   (local.get $x)
+  )
+ )
+
+ ;; CHECK:      (func $trunc_sat_u_f64_i32 (type $2) (param $x f64) (result i32)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i32.const 0)
+ ;; CHECK-NEXT: )
+ (func $trunc_sat_u_f64_i32 (param $x f64) (result i32)
+  (i32.trunc_sat_f64_u
+   (local.get $x)
+  )
+ )
+
+ ;; CHECK:      (func $trunc_sat_s_f32_i64 (type $3) (param $x f32) (result i64)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i64.const 0)
+ ;; CHECK-NEXT: )
+ (func $trunc_sat_s_f32_i64 (param $x f32) (result i64)
+  (i64.trunc_sat_f32_s
+   (local.get $x)
+  )
+ )
+
+ ;; CHECK:      (func $trunc_sat_u_f32_i64 (type $3) (param $x f32) (result i64)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i64.const 0)
+ ;; CHECK-NEXT: )
+ (func $trunc_sat_u_f32_i64 (param $x f32) (result i64)
+  (i64.trunc_sat_f32_u
+   (local.get $x)
+  )
+ )
+
+ ;; CHECK:      (func $trunc_sat_s_f64_i64 (type $4) (param $x f64) (result i64)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i64.const 0)
+ ;; CHECK-NEXT: )
+ (func $trunc_sat_s_f64_i64 (param $x f64) (result i64)
+  (i64.trunc_sat_f64_s
+   (local.get $x)
+  )
+ )
+
+ ;; CHECK:      (func $trunc_sat_u_f64_i64 (type $4) (param $x f64) (result i64)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i64.const 0)
+ ;; CHECK-NEXT: )
+ (func $trunc_sat_u_f64_i64 (param $x f64) (result i64)
+  (i64.trunc_sat_f64_u
+   (local.get $x)
+  )
+ )
+
+ ;; CHECK:      (func $supported_trunc (type $0) (param $x f32) (result i32)
+ ;; CHECK-NEXT:  (i32.trunc_f32_s
+ ;; CHECK-NEXT:   (local.get $x)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT: )
+ (func $supported_trunc (param $x f32) (result i32)
+  ;; Trapping float-to-int conversions are not stubbed out.
+  (i32.trunc_f32_s
+   (local.get $x)
+  )
+ )
+)