diff --git a/js/src/jit-test/lib/asm.js b/js/src/jit-test/lib/asm.js
index b73f5f5cbd27..fe40b6934ba2 100644
--- a/js/src/jit-test/lib/asm.js
+++ b/js/src/jit-test/lib/asm.js
@@ -34,7 +34,7 @@ function asmCompileCached()
     var quotedArgs = [];
     for (var i = 0; i < arguments.length; i++)
         quotedArgs.push("'" + arguments[i] + "'");
-    var code = "var f = new Function(" + quotedArgs.join(',') + ");assertEq(isAsmJSModule(f), true);";
+    var code = "setCachingEnabled(true); var f = new Function(" + quotedArgs.join(',') + ");assertEq(isAsmJSModule(f), true);";
     nestedShell("--js-cache", "--no-js-cache-per-process", "--execute=" + code);
 
     var f = Function.apply(null, arguments);
diff --git a/js/src/jit-test/tests/asm.js/testBullet.js b/js/src/jit-test/tests/asm.js/testBullet.js
index af51081f282f..64a6377e77c4 100644
--- a/js/src/jit-test/tests/asm.js/testBullet.js
+++ b/js/src/jit-test/tests/asm.js/testBullet.js
@@ -2,6 +2,7 @@
 // separate process and then load it again in this process, which should be a
 // cache hit.
 
+setCachingEnabled(true);
 if (!isAsmJSCompilationAvailable())
     quit();
 
@@ -9,7 +10,7 @@ if (!isAsmJSCompilationAvailable())
 // bullet.js and not the nestedShell() call, so try first commenting out
 // nestedShell() (and the loadedFromCache assertion) to see if the error
 // reproduces.
-var code = "setIonCheckGraphCoherency(false); load('" + libdir + "bullet.js'); runBullet()";
+var code = "setIonCheckGraphCoherency(false); setCachingEnabled(true); load('" + libdir + "bullet.js'); runBullet()";
 nestedShell("--js-cache", "--no-js-cache-per-process", "--execute=" + code);
 setIonCheckGraphCoherency(false);
 load(libdir + 'bullet.js');
diff --git a/js/src/jit-test/tests/asm.js/testCaching.js b/js/src/jit-test/tests/asm.js/testCaching.js
index 54469852957f..8cd3de6d7b13 100644
--- a/js/src/jit-test/tests/asm.js/testCaching.js
+++ b/js/src/jit-test/tests/asm.js/testCaching.js
@@ -1,5 +1,6 @@
 load(libdir + "asm.js");
 
+setCachingEnabled(true);
 if (!isAsmJSCompilationAvailable() || !isCachingEnabled())
     quit();
 
diff --git a/js/src/jit-test/tests/asm.js/testHeapAccess.js b/js/src/jit-test/tests/asm.js/testHeapAccess.js
index 094ef8b04446..06d1a6848406 100644
--- a/js/src/jit-test/tests/asm.js/testHeapAccess.js
+++ b/js/src/jit-test/tests/asm.js/testHeapAccess.js
@@ -15,6 +15,8 @@ var code = asmCompile('glob', 'imp', 'b', USE_ASM + HEAP_IMPORTS + 'function f(i
 var f = asmLink(code, this, null, new ArrayBuffer(4096));
 assertEq(f(0), 0);
 
+setCachingEnabled(true);
+
 var code = asmCompile('glob', 'imp', 'b', USE_ASM + HEAP_IMPORTS + 'function f(i) {i=i|0; i32[0] = i; return i8[0]|0}; return f');
 var f = asmLink(code, this, null, new ArrayBuffer(4096));
 assertEq(f(0),0);
@@ -49,6 +51,8 @@ assertEq(f(0x100),0);
     assertEq(signalHandlersBefore, signalHandlersAfter);
 })();
 
+setCachingEnabled(false);
+
 var code = asmCompile('glob', 'imp', 'b', USE_ASM + HEAP_IMPORTS + 'function f(i) {i=i|0; i32[0] = i; return u8[0]|0}; return f');
 var f = asmLink(code, this, null, new ArrayBuffer(4096));
 assertEq(f(0),0);
diff --git a/js/src/jit-test/tests/asm.js/testSource.js b/js/src/jit-test/tests/asm.js/testSource.js
index 0e671ce9d909..d5b885d1816a 100644
--- a/js/src/jit-test/tests/asm.js/testSource.js
+++ b/js/src/jit-test/tests/asm.js/testSource.js
@@ -1,3 +1,5 @@
+setCachingEnabled(true);
+
 (function() {
 /*
  * NO ARGUMENT
diff --git a/js/src/jit-test/tests/asm.js/testStackWalking.js b/js/src/jit-test/tests/asm.js/testStackWalking.js
index 719994b78d00..f3787ab92436 100644
--- a/js/src/jit-test/tests/asm.js/testStackWalking.js
+++ b/js/src/jit-test/tests/asm.js/testStackWalking.js
@@ -20,6 +20,7 @@ function dumpStack()
 setJitCompilerOption("ion.usecount.trigger", 10);
 setJitCompilerOption("baseline.usecount.trigger", 0);
 setJitCompilerOption("offthread-compilation.enable", 0);
+setCachingEnabled(true);
 
 var callFFI = asmCompile('global', 'ffis', USE_ASM + "var ffi=ffis.ffi; function f() { return ffi()|0 } return f");
 
diff --git a/js/src/jit-test/tests/asm.js/testTimeout-deactivate-reactivate-signals.js b/js/src/jit-test/tests/asm.js/testTimeout-deactivate-reactivate-signals.js
index 4240441609a1..955d32ca9b1c 100644
--- a/js/src/jit-test/tests/asm.js/testTimeout-deactivate-reactivate-signals.js
+++ b/js/src/jit-test/tests/asm.js/testTimeout-deactivate-reactivate-signals.js
@@ -2,6 +2,8 @@
 
 load(libdir + "asm.js");
 
+setCachingEnabled(true);
+
 var jco = getJitCompilerOptions();
 if (jco["signals.enable"] === 0 || !isCachingEnabled() || !isAsmJSCompilationAvailable())
     quit(6);
diff --git a/js/src/jit-test/tests/latin1/asm.js b/js/src/jit-test/tests/latin1/asm.js
index 0026d3a865bc..ace4e7f52c41 100644
--- a/js/src/jit-test/tests/latin1/asm.js
+++ b/js/src/jit-test/tests/latin1/asm.js
@@ -1,5 +1,6 @@
 load(libdir + "asm.js");
 
+setCachingEnabled(true);
 if (!isAsmJSCompilationAvailable() || !isCachingEnabled())
     quit();
 
diff --git a/js/src/shell/js.cpp b/js/src/shell/js.cpp
index 878b36f43fd4..5e33e14902ca 100644
--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -130,7 +130,7 @@ static bool enableDisassemblyDumps = false;
 static bool printTiming = false;
 static const char *jsCacheDir = nullptr;
 static const char *jsCacheAsmJSPath = nullptr;
-static bool jsCachingEnabled = true;
+static bool jsCachingEnabled = false;
 mozilla::Atomic<bool> jsCacheOpened(false);
 
 static bool