diff --git a/test/common.js b/test/common.js
index b5e3c2a13b331d..3f940789d796b6 100644
--- a/test/common.js
+++ b/test/common.js
@@ -20,6 +20,8 @@ exports.isLinuxPPCBE = (process.platform === 'linux') &&
 exports.isSunOS = process.platform === 'sunos';
 exports.isFreeBSD = process.platform === 'freebsd';
 
+exports.enoughTestMem = os.totalmem() > 0x20000000; /* 512MB */
+
 function rimrafSync(p) {
   try {
     var st = fs.lstatSync(p);
diff --git a/test/parallel/test-stringbytes-external-at-max.js b/test/parallel/test-stringbytes-external-at-max.js
index 6678e5355224b3..31f476d66b18ba 100644
--- a/test/parallel/test-stringbytes-external-at-max.js
+++ b/test/parallel/test-stringbytes-external-at-max.js
@@ -1,22 +1,32 @@
 'use strict';
+// Flags: --expose-gc
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
 // v8 fails silently if string length > v8::String::kMaxLength
 // v8::String::kMaxLength defined in v8.h
 const kStringMaxLength = process.binding('buffer').kStringMaxLength;
 
+const skipMessage =
+  '1..0 # Skipped: intensive toString tests due to memory confinements';
+if (!common.enoughTestMem) {
+  console.log(skipMessage);
+  return;
+}
+assert(typeof gc === 'function', 'Run this test with --expose-gc');
+
 try {
-  new Buffer(kStringMaxLength * 3);
+  var buf = new Buffer(kStringMaxLength);
+  // Try to allocate memory first then force gc so future allocations succeed.
+  new Buffer(2 * kStringMaxLength);
+  gc();
 } catch(e) {
-  assert.equal(e.message, 'Invalid array buffer length');
-  console.log(
-      '1..0 # Skipped: intensive toString tests due to memory confinements');
+  // If the exception is not due to memory confinement then rethrow it.
+  if (e.message !== 'Invalid array buffer length') throw (e);
+  console.log(skipMessage);
   return;
 }
 
-const buf = new Buffer(kStringMaxLength);
-
 const maxString = buf.toString('binary');
 assert.equal(maxString.length, kStringMaxLength);
diff --git a/test/parallel/test-stringbytes-external-exceed-max-by-1-ascii.js b/test/parallel/test-stringbytes-external-exceed-max-by-1-ascii.js
index e982cf9eb092fd..4789089d5e0040 100644
--- a/test/parallel/test-stringbytes-external-exceed-max-by-1-ascii.js
+++ b/test/parallel/test-stringbytes-external-exceed-max-by-1-ascii.js
@@ -1,23 +1,33 @@
 'use strict';
+// Flags: --expose-gc
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
+const skipMessage =
+  '1..0 # Skipped: intensive toString tests due to memory confinements';
+if (!common.enoughTestMem) {
+  console.log(skipMessage);
+  return;
+}
+assert(typeof gc === 'function', 'Run this test with --expose-gc');
+
 // v8 fails silently if string length > v8::String::kMaxLength
 // v8::String::kMaxLength defined in v8.h
 const kStringMaxLength = process.binding('buffer').kStringMaxLength;
 
 try {
-  new Buffer(kStringMaxLength * 3);
+  var buf = new Buffer(kStringMaxLength + 1);
+  // Try to allocate memory first then force gc so future allocations succeed.
+  new Buffer(2 * kStringMaxLength);
+  gc();
 } catch(e) {
-  assert.equal(e.message, 'Invalid array buffer length');
-  console.log(
-      '1..0 # Skipped: intensive toString tests due to memory confinements');
+  // If the exception is not due to memory confinement then rethrow it.
+  if (e.message !== 'Invalid array buffer length') throw (e);
+  console.log(skipMessage);
   return;
 }
 
-const buf = new Buffer(kStringMaxLength + 1);
-
 assert.throws(function() {
   buf.toString('ascii');
 }, /toString failed/);
diff --git a/test/parallel/test-stringbytes-external-exceed-max-by-1-base64.js b/test/parallel/test-stringbytes-external-exceed-max-by-1-base64.js
index 43a3358759e249..8f52d6ac30dd9f 100644
--- a/test/parallel/test-stringbytes-external-exceed-max-by-1-base64.js
+++ b/test/parallel/test-stringbytes-external-exceed-max-by-1-base64.js
@@ -1,23 +1,33 @@
 'use strict';
+// Flags: --expose-gc
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
+const skipMessage =
+  '1..0 # Skipped: intensive toString tests due to memory confinements';
+if (!common.enoughTestMem) {
+  console.log(skipMessage);
+  return;
+}
+assert(typeof gc === 'function', 'Run this test with --expose-gc');
+
 // v8 fails silently if string length > v8::String::kMaxLength
 // v8::String::kMaxLength defined in v8.h
 const kStringMaxLength = process.binding('buffer').kStringMaxLength;
 
 try {
-  new Buffer(kStringMaxLength * 3);
+  var buf = new Buffer(kStringMaxLength + 1);
+  // Try to allocate memory first then force gc so future allocations succeed.
+  new Buffer(2 * kStringMaxLength);
+  gc();
 } catch(e) {
-  assert.equal(e.message, 'Invalid array buffer length');
-  console.log(
-      '1..0 # Skipped: intensive toString tests due to memory confinements');
+  // If the exception is not due to memory confinement then rethrow it.
+  if (e.message !== 'Invalid array buffer length') throw (e);
+  console.log(skipMessage);
   return;
 }
 
-const buf = new Buffer(kStringMaxLength + 1);
-
 assert.throws(function() {
   buf.toString('base64');
 }, /toString failed/);
diff --git a/test/parallel/test-stringbytes-external-exceed-max-by-1-binary.js b/test/parallel/test-stringbytes-external-exceed-max-by-1-binary.js
index 9d0d2c3e897057..79dac9cc41dcf0 100644
--- a/test/parallel/test-stringbytes-external-exceed-max-by-1-binary.js
+++ b/test/parallel/test-stringbytes-external-exceed-max-by-1-binary.js
@@ -1,23 +1,33 @@
 'use strict';
+// Flags: --expose-gc
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
+const skipMessage =
+  '1..0 # Skipped: intensive toString tests due to memory confinements';
+if (!common.enoughTestMem) {
+  console.log(skipMessage);
+  return;
+}
+assert(typeof gc === 'function', 'Run this test with --expose-gc');
+
 // v8 fails silently if string length > v8::String::kMaxLength
 // v8::String::kMaxLength defined in v8.h
 const kStringMaxLength = process.binding('buffer').kStringMaxLength;
 
 try {
-  new Buffer(kStringMaxLength * 3);
+  var buf = new Buffer(kStringMaxLength + 1);
+  // Try to allocate memory first then force gc so future allocations succeed.
+  new Buffer(2 * kStringMaxLength);
+  gc();
 } catch(e) {
-  assert.equal(e.message, 'Invalid array buffer length');
-  console.log(
-      '1..0 # Skipped: intensive toString tests due to memory confinements');
+  // If the exception is not due to memory confinement then rethrow it.
+  if (e.message !== 'Invalid array buffer length') throw (e);
+  console.log(skipMessage);
   return;
 }
 
-const buf = new Buffer(kStringMaxLength + 1);
-
 assert.throws(function() {
   buf.toString('binary');
 }, /toString failed/);
diff --git a/test/parallel/test-stringbytes-external-exceed-max-by-1-hex.js b/test/parallel/test-stringbytes-external-exceed-max-by-1-hex.js
index 2937b4aab85813..50d0dad5829160 100644
--- a/test/parallel/test-stringbytes-external-exceed-max-by-1-hex.js
+++ b/test/parallel/test-stringbytes-external-exceed-max-by-1-hex.js
@@ -1,23 +1,33 @@
 'use strict';
+// Flags: --expose-gc
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
+const skipMessage =
+  '1..0 # Skipped: intensive toString tests due to memory confinements';
+if (!common.enoughTestMem) {
+  console.log(skipMessage);
+  return;
+}
+assert(typeof gc === 'function', 'Run this test with --expose-gc');
+
 // v8 fails silently if string length > v8::String::kMaxLength
 // v8::String::kMaxLength defined in v8.h
 const kStringMaxLength = process.binding('buffer').kStringMaxLength;
 
 try {
-  new Buffer(kStringMaxLength * 3);
+  var buf = new Buffer(kStringMaxLength + 1);
+  // Try to allocate memory first then force gc so future allocations succeed.
+  new Buffer(2 * kStringMaxLength);
+  gc();
 } catch(e) {
-  assert.equal(e.message, 'Invalid array buffer length');
-  console.log(
-      '1..0 # Skipped: intensive toString tests due to memory confinements');
+  // If the exception is not due to memory confinement then rethrow it.
+  if (e.message !== 'Invalid array buffer length') throw (e);
+  console.log(skipMessage);
   return;
 }
 
-const buf = new Buffer(kStringMaxLength + 1);
-
 assert.throws(function() {
   buf.toString('hex');
 }, /toString failed/);
diff --git a/test/parallel/test-stringbytes-external-exceed-max-by-1-utf8.js b/test/parallel/test-stringbytes-external-exceed-max-by-1-utf8.js
index ee297a880dacbd..ecd6eaf954e191 100644
--- a/test/parallel/test-stringbytes-external-exceed-max-by-1-utf8.js
+++ b/test/parallel/test-stringbytes-external-exceed-max-by-1-utf8.js
@@ -1,23 +1,33 @@
 'use strict';
+// Flags: --expose-gc
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
+const skipMessage =
+  '1..0 # Skipped: intensive toString tests due to memory confinements';
+if (!common.enoughTestMem) {
+  console.log(skipMessage);
+  return;
+}
+assert(typeof gc === 'function', 'Run this test with --expose-gc');
+
 // v8 fails silently if string length > v8::String::kMaxLength
 // v8::String::kMaxLength defined in v8.h
 const kStringMaxLength = process.binding('buffer').kStringMaxLength;
 
 try {
-  new Buffer(kStringMaxLength * 3);
+  var buf = new Buffer(kStringMaxLength + 1);
+  // Try to allocate memory first then force gc so future allocations succeed.
+  new Buffer(2 * kStringMaxLength);
+  gc();
 } catch(e) {
-  assert.equal(e.message, 'Invalid array buffer length');
-  console.log(
-      '1..0 # Skipped: intensive toString tests due to memory confinements');
+  // If the exception is not due to memory confinement then rethrow it.
+  if (e.message !== 'Invalid array buffer length') throw (e);
+  console.log(skipMessage);
   return;
 }
 
-const buf = new Buffer(kStringMaxLength + 1);
-
 assert.throws(function() {
   buf.toString();
 }, /toString failed|Invalid array buffer length/);
diff --git a/test/parallel/test-stringbytes-external-exceed-max-by-2.js b/test/parallel/test-stringbytes-external-exceed-max-by-2.js
index 879e4ae91dfb60..8350c4532eafdc 100644
--- a/test/parallel/test-stringbytes-external-exceed-max-by-2.js
+++ b/test/parallel/test-stringbytes-external-exceed-max-by-2.js
@@ -1,22 +1,32 @@
 'use strict';
+// Flags: --expose-gc
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
+const skipMessage =
+  '1..0 # Skipped: intensive toString tests due to memory confinements';
+if (!common.enoughTestMem) {
+  console.log(skipMessage);
+  return;
+}
+assert(typeof gc === 'function', 'Run this test with --expose-gc');
+
 // v8 fails silently if string length > v8::String::kMaxLength
 // v8::String::kMaxLength defined in v8.h
 const kStringMaxLength = process.binding('buffer').kStringMaxLength;
 
 try {
-  new Buffer(kStringMaxLength * 3);
+  var buf = new Buffer(kStringMaxLength + 2);
+  // Try to allocate memory first then force gc so future allocations succeed.
+  new Buffer(2 * kStringMaxLength);
+  gc();
 } catch(e) {
-  assert.equal(e.message, 'Invalid array buffer length');
-  console.log(
-      '1..0 # Skipped: intensive toString tests due to memory confinements');
+  // If the exception is not due to memory confinement then rethrow it.
+  if (e.message !== 'Invalid array buffer length') throw (e);
+  console.log(skipMessage);
   return;
 }
 
-const buf2 = new Buffer(kStringMaxLength + 2);
-
-const maxString = buf2.toString('utf16le');
+const maxString = buf.toString('utf16le');
 assert.equal(maxString.length, (kStringMaxLength + 2) / 2);
diff --git a/test/parallel/test-stringbytes-external-exceed-max.js b/test/parallel/test-stringbytes-external-exceed-max.js
index 0a6f585b66f3ad..fd19cfb9e20697 100644
--- a/test/parallel/test-stringbytes-external-exceed-max.js
+++ b/test/parallel/test-stringbytes-external-exceed-max.js
@@ -1,23 +1,33 @@
 'use strict';
+// Flags: --expose-gc
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
+const skipMessage =
+  '1..0 # Skipped: intensive toString tests due to memory confinements';
+if (!common.enoughTestMem) {
+  console.log(skipMessage);
+  return;
+}
+assert(typeof gc === 'function', 'Run this test with --expose-gc');
+
 // v8 fails silently if string length > v8::String::kMaxLength
 // v8::String::kMaxLength defined in v8.h
 const kStringMaxLength = process.binding('buffer').kStringMaxLength;
 
 try {
-  new Buffer(kStringMaxLength * 3);
+  var buf = new Buffer(kStringMaxLength * 2 + 2);
+  // Try to allocate memory first then force gc so future allocations succeed.
+  new Buffer(2 * kStringMaxLength);
+  gc();
 } catch(e) {
-  assert.equal(e.message, 'Invalid array buffer length');
-  console.log(
-      '1..0 # Skipped: intensive toString tests due to memory confinements');
+  // If the exception is not due to memory confinement then rethrow it.
+  if (e.message !== 'Invalid array buffer length') throw (e);
+  console.log(skipMessage);
   return;
 }
 
-const buf0 = new Buffer(kStringMaxLength * 2 + 2);
-
 assert.throws(function() {
-  buf0.toString('utf16le');
+  buf.toString('utf16le');
 }, /toString failed/);