Index: lib/Target/WebAssembly/WebAssemblyRegColoring.cpp
===================================================================
--- lib/Target/WebAssembly/WebAssemblyRegColoring.cpp
+++ lib/Target/WebAssembly/WebAssemblyRegColoring.cpp
@@ -29,10 +29,6 @@
 
 #define DEBUG_TYPE "wasm-reg-coloring"
 
-static cl::opt<bool>
-    DisableRegColoring("disable-wasm-reg-coloring", cl::Hidden, cl::init(false),
-                       cl::desc("Disable WebAssembly register coloring"));
-
 namespace {
 class WebAssemblyRegColoring final : public MachineFunctionPass {
 public:
@@ -80,9 +76,6 @@
            << "********** Function: " << MF.getName() << '\n';
   });
 
-  if (DisableRegColoring)
-    return false;
-
   // If there are calls to setjmp or sigsetjmp, don't perform coloring. Virtual
   // registers could be modified before the longjmp is executed, resulting in
   // the wrong value being used afterwards. (See <rdar://problem/8007500>.)
Index: lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
===================================================================
--- lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -185,11 +185,14 @@
   // Fails with: should be run after register allocation.
   disablePass(&MachineCopyPropagationID);
 
-  // Mark registers as representing wasm's expression stack.
-  addPass(createWebAssemblyRegStackify());
 
-  // Run the register coloring pass to reduce the total number of registers.
-  addPass(createWebAssemblyRegColoring());
+  if (getOptLevel() != CodeGenOpt::None) {
+    // Mark registers as representing wasm's expression stack.
+    addPass(createWebAssemblyRegStackify());
+
+    // Run the register coloring pass to reduce the total number of registers.
+    addPass(createWebAssemblyRegColoring());
+  }
 
   TargetPassConfig::addPostRegAlloc();