diff --git a/test/BCGen/HBC/debug_info.js b/test/BCGen/HBC/debug_info.js
index c2036215099..e78164b8a55 100644
--- a/test/BCGen/HBC/debug_info.js
+++ b/test/BCGen/HBC/debug_info.js
@@ -5,8 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-bytecode -target=HBC -g %s | %FileCheck %s --match-full-lines
-// RUN: cp %s %T/debug_info_à.js && %hermes -dump-bytecode -target=HBC -g %T/debug_info_à.js | %FileCheck %s --match-full-lines --check-prefix=UNICODE
+// RUN: %hermes -O0 -dump-bytecode -target=HBC -g %s | %FileCheck %s --match-full-lines
+// RUN: cp %s %T/debug_info_à.js && %hermes -O0 -dump-bytecode -target=HBC -g %T/debug_info_à.js | %FileCheck %s --match-full-lines --check-prefix=UNICODE
 
 var v1g = "global";
 
diff --git a/test/BCGen/HBC/es6/generator.js b/test/BCGen/HBC/es6/generator.js
index 2f2f18de4c0..318cdcd6fcb 100644
--- a/test/BCGen/HBC/es6/generator.js
+++ b/test/BCGen/HBC/es6/generator.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-bytecode %s | %FileCheck %s --match-full-lines
+// RUN: %hermesc -O0 -dump-bytecode %s | %FileCheck %s --match-full-lines
 
 function *loop(x) {
   var i = 0;
diff --git a/test/BCGen/HBC/es6/spread-arguments.js b/test/BCGen/HBC/es6/spread-arguments.js
index a126f90e136..e05beaa4eaa 100644
--- a/test/BCGen/HBC/es6/spread-arguments.js
+++ b/test/BCGen/HBC/es6/spread-arguments.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-bytecode %s | %FileCheck %s --match-full-lines
+// RUN: %hermesc -O0 -dump-bytecode %s | %FileCheck %s --match-full-lines
 
 function foo(fn, x) {
   fn(...x);
diff --git a/test/BCGen/HBC/es6/tdz-check.js b/test/BCGen/HBC/es6/tdz-check.js
index 9fd3239a317..25acef29ad9 100644
--- a/test/BCGen/HBC/es6/tdz-check.js
+++ b/test/BCGen/HBC/es6/tdz-check.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -target=HBC -dump-bytecode %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -target=HBC -dump-bytecode %s | %FileCheck --match-full-lines %s
 
 function foo() {
     return x;
diff --git a/test/BCGen/HBC/own_properties.js b/test/BCGen/HBC/own_properties.js
index b53d7694394..d5631ae6c58 100644
--- a/test/BCGen/HBC/own_properties.js
+++ b/test/BCGen/HBC/own_properties.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -target=HBC -dump-lir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -target=HBC -dump-lir %s | %FileCheck --match-full-lines %s
 
 // Test that StoreNewOwnPropertyInst is lowered to StoreOwnPropertyInst when
 // the property name is a valid array index.
diff --git a/test/BCGen/HBC/unique-lit.js b/test/BCGen/HBC/unique-lit.js
index 99093361a7f..0b4103db0e8 100644
--- a/test/BCGen/HBC/unique-lit.js
+++ b/test/BCGen/HBC/unique-lit.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-bytecode %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-bytecode %s | %FileCheck --match-full-lines %s
 // RUN: %hermesc -O -dump-bytecode %s | %FileCheck --match-full-lines  --check-prefix=CHKOPT %s
 
 // Check that literals are uniqued when optimizations is disabled, but aren't
diff --git a/test/BCGen/HBC/variables.js b/test/BCGen/HBC/variables.js
index e81a0b340ac..2e1fede822d 100644
--- a/test/BCGen/HBC/variables.js
+++ b/test/BCGen/HBC/variables.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -strict -target=HBC -dump-lir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -strict -O0 -target=HBC -dump-lir %s | %FileCheck --match-full-lines %s
 // RUN: %hermes -strict -O -target=HBC -dump-lir %s | %FileCheck --match-full-lines --check-prefix=CHKOPT %s
 
 var a = 5;
diff --git a/test/IRGen/__proto__.js b/test/IRGen/__proto__.js
index 67e83233289..49291d2688f 100644
--- a/test/IRGen/__proto__.js
+++ b/test/IRGen/__proto__.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 // Ensure that __proto__ is not set as an "own" property.
 
diff --git a/test/IRGen/accessors.js b/test/IRGen/accessors.js
index 13123e0d597..87e73d4739d 100644
--- a/test/IRGen/accessors.js
+++ b/test/IRGen/accessors.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck --match-full-lines %s
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 var x = {
diff --git a/test/IRGen/arguments.js b/test/IRGen/arguments.js
index 879d1dcbf1e..151b65bd686 100644
--- a/test/IRGen/arguments.js
+++ b/test/IRGen/arguments.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir -non-strict %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir -non-strict %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir -non-strict %s -O
 
 // Code that doesn't require creation of the expensive object.
diff --git a/test/IRGen/array_elision.js b/test/IRGen/array_elision.js
index 7a4a40a6ce9..3fc67a76d85 100644
--- a/test/IRGen/array_elision.js
+++ b/test/IRGen/array_elision.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/array_object.js b/test/IRGen/array_object.js
index 446b4b39d9f..9f06aa5212a 100644
--- a/test/IRGen/array_object.js
+++ b/test/IRGen/array_object.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/assignment.js b/test/IRGen/assignment.js
index 2afc6e5b73a..e2672b7d230 100644
--- a/test/IRGen/assignment.js
+++ b/test/IRGen/assignment.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/binary_operator.js b/test/IRGen/binary_operator.js
index d82024d34d4..cdfee09d71d 100644
--- a/test/IRGen/binary_operator.js
+++ b/test/IRGen/binary_operator.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
   function foo(x, y) {
diff --git a/test/IRGen/break_block.js b/test/IRGen/break_block.js
index f8ee286262f..253a3915c1a 100644
--- a/test/IRGen/break_block.js
+++ b/test/IRGen/break_block.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 var x = 0;
diff --git a/test/IRGen/break_context_in_finally.js b/test/IRGen/break_context_in_finally.js
index 2be6c2f4ea1..8a2452a26d4 100644
--- a/test/IRGen/break_context_in_finally.js
+++ b/test/IRGen/break_context_in_finally.js
@@ -5,8 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck %s --match-full-lines
-// RUN: %hermesc -dump-bytecode %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermesc -O0 -dump-bytecode %s
 
 // Ensure that the "break" in the finally handler exits the correct
 // loop.
diff --git a/test/IRGen/call_expr.js b/test/IRGen/call_expr.js
index cb5a47dbd2b..70af5430a11 100644
--- a/test/IRGen/call_expr.js
+++ b/test/IRGen/call_expr.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 //CHECK: function bar(x, y, z)
diff --git a/test/IRGen/cjs/cjs-location.js b/test/IRGen/cjs/cjs-location.js
index 7128debf8f0..37616a09d76 100644
--- a/test/IRGen/cjs/cjs-location.js
+++ b/test/IRGen/cjs/cjs-location.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -commonjs -dump-ir -dump-source-location < %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -commonjs -dump-ir -dump-source-location < %s | %FileCheck --match-full-lines %s
 
 x = 10;
 
diff --git a/test/IRGen/cjs/cjs-multiple-1.js b/test/IRGen/cjs/cjs-multiple-1.js
index bd213e5d693..beee7c55a91 100644
--- a/test/IRGen/cjs/cjs-multiple-1.js
+++ b/test/IRGen/cjs/cjs-multiple-1.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -commonjs -dump-ir %S/cjs-multiple-1.js %S/cjs-multiple-2.js | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -commonjs -dump-ir %S/cjs-multiple-1.js %S/cjs-multiple-2.js | %FileCheck --match-full-lines %s
 
 print('done 1');
 
diff --git a/test/IRGen/cjs/cjs-simple.js b/test/IRGen/cjs/cjs-simple.js
index 2d7c7b1f46a..ed222b0412e 100644
--- a/test/IRGen/cjs/cjs-simple.js
+++ b/test/IRGen/cjs/cjs-simple.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -commonjs -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -commonjs -dump-ir %s | %FileCheck --match-full-lines %s
 
 print('done');
 
diff --git a/test/IRGen/cond_expr_phi.js b/test/IRGen/cond_expr_phi.js
index d5184eb492b..c6254c329ce 100644
--- a/test/IRGen/cond_expr_phi.js
+++ b/test/IRGen/cond_expr_phi.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -dump-ir %s -O
 
 function condExpr(a,b,c,d) {
diff --git a/test/IRGen/custom_globals.js b/test/IRGen/custom_globals.js
index 9dcca059e4a..2564c0ac753 100644
--- a/test/IRGen/custom_globals.js
+++ b/test/IRGen/custom_globals.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir -include-globals %s.d %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir -include-globals %s.d %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir -include-globals %s.d %s -O
 
 var x = CustomGlobalProperty;
diff --git a/test/IRGen/debugger.js b/test/IRGen/debugger.js
index e2f88b4b29b..bbc33a5c522 100644
--- a/test/IRGen/debugger.js
+++ b/test/IRGen/debugger.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 function foo () {
diff --git a/test/IRGen/delete-in-catch.js b/test/IRGen/delete-in-catch.js
index dae17364b61..975d8f0b29b 100644
--- a/test/IRGen/delete-in-catch.js
+++ b/test/IRGen/delete-in-catch.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 
 // Ensure that catch variables are not treated as global.
 var result;
diff --git a/test/IRGen/delete.js b/test/IRGen/delete.js
index 4522a3ea8b8..da6198603a0 100644
--- a/test/IRGen/delete.js
+++ b/test/IRGen/delete.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 function sink() {}
diff --git a/test/IRGen/do_while.js b/test/IRGen/do_while.js
index 2ea84c482f7..d47aaf081d1 100644
--- a/test/IRGen/do_while.js
+++ b/test/IRGen/do_while.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 //CHECK-LABEL:function simple_do_while_test(cond)
diff --git a/test/IRGen/es6/array-binding.js b/test/IRGen/es6/array-binding.js
index c4cdb2f696c..f426f780a29 100644
--- a/test/IRGen/es6/array-binding.js
+++ b/test/IRGen/es6/array-binding.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 var [a, [b = 1, c] = [,2]] = x;
 
diff --git a/test/IRGen/es6/array-spread.js b/test/IRGen/es6/array-spread.js
index bdb52d5fdab..24630f9f4ad 100644
--- a/test/IRGen/es6/array-spread.js
+++ b/test/IRGen/es6/array-spread.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 // RUN: %hermesc -O -dump-ir %s | %FileCheck --match-full-lines -check-prefix OPT %s
 
 function foo(x) {
diff --git a/test/IRGen/es6/arrow-arguments.js b/test/IRGen/es6/arrow-arguments.js
index 10685113d83..e0fe36315de 100644
--- a/test/IRGen/es6/arrow-arguments.js
+++ b/test/IRGen/es6/arrow-arguments.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 // Ensure that 'arguments' is captured correctly for arrow functions.
 
diff --git a/test/IRGen/es6/arrow-function-1.js b/test/IRGen/es6/arrow-function-1.js
index 047c1508030..60829de4e00 100644
--- a/test/IRGen/es6/arrow-function-1.js
+++ b/test/IRGen/es6/arrow-function-1.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 var func1 = () => 10;
 //CHECK-LABEL:arrow func1()
diff --git a/test/IRGen/es6/arrow-function-2.js b/test/IRGen/es6/arrow-function-2.js
index 17ad46ae759..7db9cba6a8b 100644
--- a/test/IRGen/es6/arrow-function-2.js
+++ b/test/IRGen/es6/arrow-function-2.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function outer1() {
     var innerArrow1 = () => this.x;
diff --git a/test/IRGen/es6/arrow-function-3.js b/test/IRGen/es6/arrow-function-3.js
index bc7871ca390..38f1567fc96 100644
--- a/test/IRGen/es6/arrow-function-3.js
+++ b/test/IRGen/es6/arrow-function-3.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function foo(x = () => this) {
     return x();
diff --git a/test/IRGen/es6/computed-props.js b/test/IRGen/es6/computed-props.js
index 118c84ee0fe..d51d2a30da6 100644
--- a/test/IRGen/es6/computed-props.js
+++ b/test/IRGen/es6/computed-props.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -dump-ir %s | %FileCheck %s --match-full-lines
 
 ({
   ['x']: 3,
diff --git a/test/IRGen/es6/disable-tdz.js b/test/IRGen/es6/disable-tdz.js
index 69bdf1eafec..65e512b6d53 100644
--- a/test/IRGen/es6/disable-tdz.js
+++ b/test/IRGen/es6/disable-tdz.js
@@ -5,8 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
-// RUN: %hermesc -fno-enable-tdz -dump-ir %s | %FileCheck --match-full-lines --check-prefix=CHKDIS %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -fno-enable-tdz -dump-ir %s | %FileCheck --match-full-lines --check-prefix=CHKDIS %s
 
 function check1() {
     return x + y;
diff --git a/test/IRGen/es6/for-of.js b/test/IRGen/es6/for-of.js
index 6bef2d85cf9..d6e95907ec7 100644
--- a/test/IRGen/es6/for-of.js
+++ b/test/IRGen/es6/for-of.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function forof_normal(seq, cb) {
     for(var i of seq)
diff --git a/test/IRGen/es6/generator.js b/test/IRGen/es6/generator.js
index 0f02aefa22a..99a5906e26e 100644
--- a/test/IRGen/es6/generator.js
+++ b/test/IRGen/es6/generator.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck %s --match-full-lines
 
 function* simple() {
   yield 1;
diff --git a/test/IRGen/es6/new-target.js b/test/IRGen/es6/new-target.js
index e582f3056d8..047617b2746 100644
--- a/test/IRGen/es6/new-target.js
+++ b/test/IRGen/es6/new-target.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function func1() {
     return new.target;
diff --git a/test/IRGen/es6/object-binding.js b/test/IRGen/es6/object-binding.js
index e6f73f57f22..020ef4162a9 100644
--- a/test/IRGen/es6/object-binding.js
+++ b/test/IRGen/es6/object-binding.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck %s --match-full-lines
 
 //CHECK-LABEL:function global()
 //CHECK-NEXT:frame = [], globals = [a, b, d, e]
diff --git a/test/IRGen/es6/object-computed-destructuring.js b/test/IRGen/es6/object-computed-destructuring.js
index 33424cb8240..29b320c6af6 100644
--- a/test/IRGen/es6/object-computed-destructuring.js
+++ b/test/IRGen/es6/object-computed-destructuring.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck %s --match-full-lines
 
 // CHECK-LABEL: function global()
 // CHECK-NEXT: frame = [], globals = [b, rest, d]
diff --git a/test/IRGen/es6/param-init-arguments.js b/test/IRGen/es6/param-init-arguments.js
index a3ace610596..2e8bf65ffff 100644
--- a/test/IRGen/es6/param-init-arguments.js
+++ b/test/IRGen/es6/param-init-arguments.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 // Ensure that we can use "arguments" when initializing formal parameters.
 
diff --git a/test/IRGen/es6/rest-element.js b/test/IRGen/es6/rest-element.js
index df01ccb4d32..fb442de5b6c 100644
--- a/test/IRGen/es6/rest-element.js
+++ b/test/IRGen/es6/rest-element.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function f1(t) {
     var [...a] = t;
diff --git a/test/IRGen/es6/rest-param.js b/test/IRGen/es6/rest-param.js
index 7b193b05529..27d6384272e 100644
--- a/test/IRGen/es6/rest-param.js
+++ b/test/IRGen/es6/rest-param.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function f1(a, ...b) {}
 //CHECK-LABEL: function f1(a)
diff --git a/test/IRGen/es6/rest-property.js b/test/IRGen/es6/rest-property.js
index 92dcaaed296..14de2480ebd 100644
--- a/test/IRGen/es6/rest-property.js
+++ b/test/IRGen/es6/rest-property.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function f1(t) {
     var {...a} = t;
diff --git a/test/IRGen/es6/spread-arguments.js b/test/IRGen/es6/spread-arguments.js
index 773df88724d..1d55874d3f3 100644
--- a/test/IRGen/es6/spread-arguments.js
+++ b/test/IRGen/es6/spread-arguments.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -dump-ir -O0 %s | %FileCheck --match-full-lines %s
 // RUN: %hermes -dump-ir -O %s | %FileCheck --match-full-lines -check-prefix=OPT %s
 
 function foo(fn, x) {
diff --git a/test/IRGen/es6/spread-operator.js b/test/IRGen/es6/spread-operator.js
index e9a5b9f1d18..1753d847cc5 100644
--- a/test/IRGen/es6/spread-operator.js
+++ b/test/IRGen/es6/spread-operator.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function foo(a, b, c) {
     return {a, ...b, c};
diff --git a/test/IRGen/es6/tdz-check.js b/test/IRGen/es6/tdz-check.js
index 0fb61c264f3..b1cca6cffc3 100644
--- a/test/IRGen/es6/tdz-check.js
+++ b/test/IRGen/es6/tdz-check.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function check1() {
     return x + y;
diff --git a/test/IRGen/escape_strings.js b/test/IRGen/escape_strings.js
index 417f6f67307..57263b4ab70 100644
--- a/test/IRGen/escape_strings.js
+++ b/test/IRGen/escape_strings.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/esm/esm-default.js b/test/IRGen/esm/esm-default.js
index 86e243ffd6d..dd98458238f 100644
--- a/test/IRGen/esm/esm-default.js
+++ b/test/IRGen/esm/esm-default.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -commonjs -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -commonjs -dump-ir %s | %FileCheck --match-full-lines %s
 
 export default function() {
   return 400;
diff --git a/test/IRGen/esm/esm-export.js b/test/IRGen/esm/esm-export.js
index 7efffb0d2bc..834965761d5 100644
--- a/test/IRGen/esm/esm-export.js
+++ b/test/IRGen/esm/esm-export.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -commonjs -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -commonjs -dump-ir %s | %FileCheck --match-full-lines %s
 
 // CHECK-LABEL: function cjs_module(exports, require, module)
 // CHECK-NEXT: frame = [x, y, z, longVariableName, a, myFun, exports, require, module]
diff --git a/test/IRGen/esm/esm-import.js b/test/IRGen/esm/esm-import.js
index 9d3bb2f5015..61c15beb0cc 100644
--- a/test/IRGen/esm/esm-import.js
+++ b/test/IRGen/esm/esm-import.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -commonjs -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -commonjs -dump-ir %s | %FileCheck --match-full-lines %s
 
 // CHECK-LABEL: function cjs_module(exports, require, module)
 // CHECK-NEXT: frame = [Foo, defaultFoo, x, z, exports, require, module]
diff --git a/test/IRGen/eval.js b/test/IRGen/eval.js
index 71c3ce14371..dabc2cee60d 100644
--- a/test/IRGen/eval.js
+++ b/test/IRGen/eval.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function foo() {
     return eval("1 + 1");
diff --git a/test/IRGen/for_in_loops.js b/test/IRGen/for_in_loops.js
index 94bc448bbec..f7affa1ef82 100644
--- a/test/IRGen/for_in_loops.js
+++ b/test/IRGen/for_in_loops.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 function sink(a) { }
diff --git a/test/IRGen/for_in_prop_access.js b/test/IRGen/for_in_prop_access.js
index 2b35a4dcf82..30a9e7d344d 100644
--- a/test/IRGen/for_in_prop_access.js
+++ b/test/IRGen/for_in_prop_access.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 //CHECK-LABEL:function simple_loop(obj)
diff --git a/test/IRGen/for_in_var_init.js b/test/IRGen/for_in_var_init.js
index a410b045f9e..c0615d2d294 100644
--- a/test/IRGen/for_in_var_init.js
+++ b/test/IRGen/for_in_var_init.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermesc -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermesc -dump-ir %s -O
 
 function foo(obj) {
diff --git a/test/IRGen/for_loops.js b/test/IRGen/for_loops.js
index e66d257b0b0..6070ca2fa87 100644
--- a/test/IRGen/for_loops.js
+++ b/test/IRGen/for_loops.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 function sink(a) { }
diff --git a/test/IRGen/func_expr.js b/test/IRGen/func_expr.js
index 61053c6c02d..8a5a09a7479 100644
--- a/test/IRGen/func_expr.js
+++ b/test/IRGen/func_expr.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 //CHECK: function test0()
diff --git a/test/IRGen/global_properties.js b/test/IRGen/global_properties.js
index f38f54ab7d1..ede4ead716b 100644
--- a/test/IRGen/global_properties.js
+++ b/test/IRGen/global_properties.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 //CHECK: function global()
diff --git a/test/IRGen/if_stmt.js b/test/IRGen/if_stmt.js
index 52302bd1dc9..2b621a957fb 100644
--- a/test/IRGen/if_stmt.js
+++ b/test/IRGen/if_stmt.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 function main(boop) {
diff --git a/test/IRGen/instance_of.js b/test/IRGen/instance_of.js
index 610038ce944..ce896562ed6 100644
--- a/test/IRGen/instance_of.js
+++ b/test/IRGen/instance_of.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ra %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -dump-ra %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -dump-ra %s -O
 
 //CHECK-LABEL:function simple_test0(x, y)
diff --git a/test/IRGen/json.js b/test/IRGen/json.js
index 45819360dda..d7f2855ce2a 100644
--- a/test/IRGen/json.js
+++ b/test/IRGen/json.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/literals.js b/test/IRGen/literals.js
index ef2a35eefac..c65f1d39f57 100644
--- a/test/IRGen/literals.js
+++ b/test/IRGen/literals.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 function foo() {
diff --git a/test/IRGen/logical_expr.js b/test/IRGen/logical_expr.js
index 1c1ffc9d3b9..2fcea2c9453 100644
--- a/test/IRGen/logical_expr.js
+++ b/test/IRGen/logical_expr.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 //CHECK:function logical_and(y, x)
diff --git a/test/IRGen/mutiple_decls.js b/test/IRGen/mutiple_decls.js
index 70ddf1e18b3..85dc67008a8 100644
--- a/test/IRGen/mutiple_decls.js
+++ b/test/IRGen/mutiple_decls.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 // Make sure that multiple declarations are collapsed into one.
diff --git a/test/IRGen/nested_cond.js b/test/IRGen/nested_cond.js
index eee247dd067..093adec8f3b 100644
--- a/test/IRGen/nested_cond.js
+++ b/test/IRGen/nested_cond.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function foo (a, b, c) {
     if (!(!a && c || b && !c))
diff --git a/test/IRGen/new_expr.js b/test/IRGen/new_expr.js
index a8ba2539e35..df6b365dbbd 100644
--- a/test/IRGen/new_expr.js
+++ b/test/IRGen/new_expr.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 function Car(model, year) {
diff --git a/test/IRGen/non-simple-params.js b/test/IRGen/non-simple-params.js
index 4b4b2465b0e..d34ae834e71 100644
--- a/test/IRGen/non-simple-params.js
+++ b/test/IRGen/non-simple-params.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -dump-ir %s | %FileCheck %s --match-full-lines
 
 function foo(a, b = a) {
     return a + b;
diff --git a/test/IRGen/object_literals.js b/test/IRGen/object_literals.js
index 40902462329..7b406efcf71 100644
--- a/test/IRGen/object_literals.js
+++ b/test/IRGen/object_literals.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 ({prop1: 10});
diff --git a/test/IRGen/own_props.js b/test/IRGen/own_props.js
index 0d7ae87f09b..94661a81d7f 100644
--- a/test/IRGen/own_props.js
+++ b/test/IRGen/own_props.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 ({10: 1, "11": 2, "10": 3})
 
diff --git a/test/IRGen/properties.js b/test/IRGen/properties.js
index f7e63af4088..b5aa824ec1b 100644
--- a/test/IRGen/properties.js
+++ b/test/IRGen/properties.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/regexp.js b/test/IRGen/regexp.js
index 1b69b839a7f..4a6cc4cf2e1 100644
--- a/test/IRGen/regexp.js
+++ b/test/IRGen/regexp.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 //CHECK-LABEL:function simple_test0()
diff --git a/test/IRGen/regress-optional-init.js b/test/IRGen/regress-optional-init.js
index b37c1d1594f..e2309083a0d 100644
--- a/test/IRGen/regress-optional-init.js
+++ b/test/IRGen/regress-optional-init.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 //
 // Make sure that the optional initialization generates a correct Phi node, when the initialization
 // is multi-block.
diff --git a/test/IRGen/return_stmt.js b/test/IRGen/return_stmt.js
index 251bb836ca1..a34a0246433 100644
--- a/test/IRGen/return_stmt.js
+++ b/test/IRGen/return_stmt.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 //CHECK: function test0(x, y)
diff --git a/test/IRGen/sequence.js b/test/IRGen/sequence.js
index 229c0e55a98..5d05326fdca 100644
--- a/test/IRGen/sequence.js
+++ b/test/IRGen/sequence.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 function sink0(a) { }
diff --git a/test/IRGen/source_loc.js b/test/IRGen/source_loc.js
index e4ce0a994da..611dc3c8e28 100644
--- a/test/IRGen/source_loc.js
+++ b/test/IRGen/source_loc.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-source-location -dump-ir < %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -dump-source-location -dump-ir < %s | %FileCheck --match-full-lines %s
 
 function foo(a,b) {
     if (a > b) {
diff --git a/test/IRGen/switch_dup.js b/test/IRGen/switch_dup.js
index 9f29f64cebc..d450f9365aa 100644
--- a/test/IRGen/switch_dup.js
+++ b/test/IRGen/switch_dup.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 
 function foo1(x) {
     switch (x) {
diff --git a/test/IRGen/switch_empty.js b/test/IRGen/switch_empty.js
index 5c4282ae663..b2aa96bd99a 100644
--- a/test/IRGen/switch_empty.js
+++ b/test/IRGen/switch_empty.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 function empty () {
diff --git a/test/IRGen/ternary.js b/test/IRGen/ternary.js
index 523bff0f2fd..2b0da135582 100644
--- a/test/IRGen/ternary.js
+++ b/test/IRGen/ternary.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 // Simple test.
diff --git a/test/IRGen/try_catch.js b/test/IRGen/try_catch.js
index 90e0246aed3..7b483f4451e 100644
--- a/test/IRGen/try_catch.js
+++ b/test/IRGen/try_catch.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/typeof_undefined.js b/test/IRGen/typeof_undefined.js
index 9acbba70124..4c51ec27668 100644
--- a/test/IRGen/typeof_undefined.js
+++ b/test/IRGen/typeof_undefined.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir -strict %s 2>&1 | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -hermes-parser -dump-ir -strict %s 2>&1 | %FileCheck %s --match-full-lines
 
 var x = typeof foo;
 
diff --git a/test/IRGen/unary_operator_and_delete.js b/test/IRGen/unary_operator_and_delete.js
index 5057a3227b3..34697598ca5 100644
--- a/test/IRGen/unary_operator_and_delete.js
+++ b/test/IRGen/unary_operator_and_delete.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/undeclared_strict.js b/test/IRGen/undeclared_strict.js
index 6ac661a911f..62f84e7d65a 100644
--- a/test/IRGen/undeclared_strict.js
+++ b/test/IRGen/undeclared_strict.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir -strict %s 2>&1 | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -dump-ir -strict %s 2>&1 | %FileCheck %s --match-full-lines
 
 var x = y;
 //CHECK: {{.*}}undeclared_strict.js:10:9: warning: the variable "y" was not declared in function "global"
diff --git a/test/IRGen/undeclared_strict_ignored.js b/test/IRGen/undeclared_strict_ignored.js
index 0e4f05fff75..8f3ffe58f17 100644
--- a/test/IRGen/undeclared_strict_ignored.js
+++ b/test/IRGen/undeclared_strict_ignored.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir -strict -Wno-undefined-variable %s 2>&1 | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -dump-ir -strict -Wno-undefined-variable %s 2>&1 | %FileCheck %s --match-full-lines
 
 var x = y;
 //CHECK: function global()
diff --git a/test/IRGen/undeclared_var_non_strict_mode.js b/test/IRGen/undeclared_var_non_strict_mode.js
index 3cdbdf8e3b3..b1ce31663b3 100644
--- a/test/IRGen/undeclared_var_non_strict_mode.js
+++ b/test/IRGen/undeclared_var_non_strict_mode.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s -non-strict 2>&1 | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -hermes-parser -dump-ir %s -non-strict 2>&1 | %FileCheck %s --match-full-lines
 
 //CHECK-LABEL: function one()
 //CHECK-NEXT: frame = []
diff --git a/test/IRGen/undefined.js b/test/IRGen/undefined.js
index 03f377a2f4c..ad66463bdd5 100644
--- a/test/IRGen/undefined.js
+++ b/test/IRGen/undefined.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck --match-full-lines %s
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 //CHECK-LABEL:function global()
diff --git a/test/IRGen/uninitialized_var.js b/test/IRGen/uninitialized_var.js
index 8bf03a426df..94c753c7ea6 100644
--- a/test/IRGen/uninitialized_var.js
+++ b/test/IRGen/uninitialized_var.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck --match-full-lines %s
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 //CHECK-LABEL:function global()
diff --git a/test/IRGen/update_expr.js b/test/IRGen/update_expr.js
index de018ef5cfe..961900f78e1 100644
--- a/test/IRGen/update_expr.js
+++ b/test/IRGen/update_expr.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/variable_hoisting.js b/test/IRGen/variable_hoisting.js
index 14f9f84f847..612fd9ff2cc 100644
--- a/test/IRGen/variable_hoisting.js
+++ b/test/IRGen/variable_hoisting.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/variable_hoisting_recursion.js b/test/IRGen/variable_hoisting_recursion.js
index 3b0fef40501..48c85697077 100644
--- a/test/IRGen/variable_hoisting_recursion.js
+++ b/test/IRGen/variable_hoisting_recursion.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/variables.js b/test/IRGen/variables.js
index 02b504c6e11..1bb4733a802 100644
--- a/test/IRGen/variables.js
+++ b/test/IRGen/variables.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 
diff --git a/test/IRGen/while_break_if.js b/test/IRGen/while_break_if.js
index 5d723806c04..cb832025fa1 100644
--- a/test/IRGen/while_break_if.js
+++ b/test/IRGen/while_break_if.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s -O0 | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -dump-ir %s -O
 
 function bar() { return 1 }
diff --git a/test/Optimizer/dump_use_list.js b/test/Optimizer/dump_use_list.js
index 7f767f74743..7f0976f5fd9 100644
--- a/test/Optimizer/dump_use_list.js
+++ b/test/Optimizer/dump_use_list.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s -dump-instr-uselist  | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -hermes-parser -dump-ir %s -dump-instr-uselist  | %FileCheck %s --match-full-lines
 
 //CHECK-LABEL:function foo(a, b)
 //CHECK-NEXT:frame = [c, a, b]
diff --git a/test/Optimizer/es6/tdz-dedup.js b/test/Optimizer/es6/tdz-dedup.js
index fd0614e3be7..e32d0ee07f2 100644
--- a/test/Optimizer/es6/tdz-dedup.js
+++ b/test/Optimizer/es6/tdz-dedup.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermesc -dump-ir %s | %FileCheck --match-full-lines %s
+// RUN: %hermesc -O0 -dump-ir %s | %FileCheck --match-full-lines %s
 // RUN: %hermesc -custom-opt=tdzdedup -dump-ir %s | %FileCheck --match-full-lines --check-prefix=CHKOPT %s
 
 function check_after_store(p) {
diff --git a/test/Optimizer/global_props.js b/test/Optimizer/global_props.js
index 08c1717b2dc..5b3a634f720 100644
--- a/test/Optimizer/global_props.js
+++ b/test/Optimizer/global_props.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -strict -dump-ir -include-globals=%s.d %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -strict -dump-ir -O0 -include-globals=%s.d %s | %FileCheck %s --match-full-lines
 // RUN: %hermes -hermes-parser -strict -dump-ir -O -include-globals=%s.d %s | %FileCheck %s --match-full-lines --check-prefix=OPT-CHECK
 // RUN: %hermes -hermes-parser -non-strict -dump-ir -O -include-globals=%s.d %s | %FileCheck %s --match-full-lines --check-prefix=OPT-NONSTRICT
 
diff --git a/test/Optimizer/loadstore.js b/test/Optimizer/loadstore.js
index a91408d1d62..7e1272e1c06 100644
--- a/test/Optimizer/loadstore.js
+++ b/test/Optimizer/loadstore.js
@@ -6,7 +6,7 @@
  */
 
 // RUN: %hermes -hermes-parser -strict -dump-ir %s     -O  | %FileCheck %s --match-full-lines --check-prefix=OPT-CHECK
-// RUN: %hermes -hermes-parser -strict -dump-ir %s         | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -strict -dump-ir %s     -O0 | %FileCheck %s --match-full-lines
 
 // Unoptimized:
 //CHECK-LABEL:function foo(p1)
diff --git a/test/Optimizer/variables.js b/test/Optimizer/variables.js
index bf24b6cddfa..a5373590a7d 100644
--- a/test/Optimizer/variables.js
+++ b/test/Optimizer/variables.js
@@ -6,7 +6,7 @@
  */
 
 // RUN: %hermes -hermes-parser -dump-ir %s     -O  | %FileCheck %s --match-full-lines --check-prefix=OPT-CHECK
-// RUN: %hermes -hermes-parser -dump-ir %s         | %FileCheck %s --match-full-lines
+// RUN: %hermes -hermes-parser -dump-ir %s     -O0 | %FileCheck %s --match-full-lines
 
 
 // Unoptimized:
diff --git a/test/Parser/big-number.js b/test/Parser/big-number.js
index 0b79a783c04..5b752d2bf14 100644
--- a/test/Parser/big-number.js
+++ b/test/Parser/big-number.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -dump-ir %s | %FileCheck %s --match-full-lines
 
 // This test ensures that a very large numeric literal can be parsed as
 // Infinity.
diff --git a/test/Parser/binary-expr.js b/test/Parser/binary-expr.js
index db146d1f1a3..9d14cd2e7e8 100644
--- a/test/Parser/binary-expr.js
+++ b/test/Parser/binary-expr.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -hermes-parser -dump-ir %s | %FileCheck %s --match-full-lines
 
 var r, a, b, c, d, e;
 //CHECK-LABEL:function global()
diff --git a/test/RA/assign_to_argument.js b/test/RA/assign_to_argument.js
index 401c00966c7..d78ec06855b 100644
--- a/test/RA/assign_to_argument.js
+++ b/test/RA/assign_to_argument.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ra %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -dump-ra %s | %FileCheck %s --match-full-lines
 
 //CHECK-LABEL:function foo(a)
 //CHECK-NEXT:frame = [a]
diff --git a/test/RA/callee.js b/test/RA/callee.js
index 13d1a4910da..c2285748cba 100644
--- a/test/RA/callee.js
+++ b/test/RA/callee.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: %hermes -dump-ra %s | %FileCheck %s --match-full-lines
+// RUN: %hermes -O0 -dump-ra %s | %FileCheck %s --match-full-lines
 
 function sink(x,y,z) {}
 
diff --git a/test/hermes/execution-time-limit.js b/test/hermes/execution-time-limit.js
index 96918be5c8f..8d3e1d00bbe 100644
--- a/test/hermes/execution-time-limit.js
+++ b/test/hermes/execution-time-limit.js
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: (! %hermes -emit-async-break-check -time-limit=1000 %s 2>&1 ) | %FileCheck --match-full-lines %s
+// RUN: (! %hermes -O0 -emit-async-break-check -time-limit=1000 %s 2>&1 ) | %FileCheck --match-full-lines %s
 
 function entryPoint() {
   helper();