diff --git a/CMakeLists.txt b/CMakeLists.txt
index c69489c..7c9b701 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -194,8 +194,6 @@
 option_if_not_defined(REACTOR_EMIT_ASM_FILE "Emit asm files for JIT functions" FALSE)
 option_if_not_defined(REACTOR_ENABLE_PRINT "Enable RR_PRINT macros" FALSE)
 option_if_not_defined(REACTOR_VERIFY_LLVM_IR "Check reactor-generated LLVM IR is valid even in release builds" FALSE)
-# TODO(b/155148722): Remove when unconditionally instrumenting for all build systems.
-option_if_not_defined(REACTOR_ENABLE_MEMORY_SANITIZER_INSTRUMENTATION "Include JIT in MSAN instrumentation (LLVM backend)" TRUE)
 option_if_not_defined(SWIFTSHADER_LESS_DEBUG_INFO "Generate less debug info to reduce file size" FALSE)
 option_if_not_defined(SWIFTSHADER_ENABLE_VULKAN_DEBUGGER "Enable Vulkan debugger support" FALSE)
 option_if_not_defined(SWIFTSHADER_ENABLE_ASTC "Enable ASTC compressed textures support" TRUE)  # TODO(b/150130101)
diff --git a/src/Reactor/BUILD.gn b/src/Reactor/BUILD.gn
index 86f4bc6..676f99f 100644
--- a/src/Reactor/BUILD.gn
+++ b/src/Reactor/BUILD.gn
@@ -27,11 +27,6 @@
     ]
   } else {
     cflags = [ "-Wno-unused-local-typedef" ]
-    defines = [
-      # Enable instrumentation of Reactor routines for MemorySanitizer builds (LLVM backend).
-      # TODO(b/155148722): Remove when unconditionally instrumenting for all build systems.
-      "REACTOR_ENABLE_MEMORY_SANITIZER_INSTRUMENTATION=1",
-    ]
   }
 }
 
diff --git a/src/Reactor/CMakeLists.txt b/src/Reactor/CMakeLists.txt
index e27121b..bb49a08 100644
--- a/src/Reactor/CMakeLists.txt
+++ b/src/Reactor/CMakeLists.txt
@@ -68,12 +68,6 @@
     list(APPEND REACTOR_PRIVATE_LINK_LIBRARIES Boost::boost)
 endif(REACTOR_EMIT_DEBUG_INFO)
 
-# Enable instrumentation of Reactor routines for MemorySanitizer builds (LLVM backend).
-# TODO(b/155148722): Remove when unconditionally instrumenting for all build systems.
-if(REACTOR_ENABLE_MEMORY_SANITIZER_INSTRUMENTATION)
-    list(APPEND REACTOR_PUBLIC_COMPILE_DEFINITIONS "REACTOR_ENABLE_MEMORY_SANITIZER_INSTRUMENTATION")
-endif()
-
 list(APPEND REACTOR_PRIVATE_COMPILE_DEFINITIONS "REACTOR_ANONYMOUS_MMAP_NAME=swiftshader_jit")
 
 # SubzeroReactor library
diff --git a/src/Reactor/LLVMJIT.cpp b/src/Reactor/LLVMJIT.cpp
index 6fe0ff2..b284aa0 100644
--- a/src/Reactor/LLVMJIT.cpp
+++ b/src/Reactor/LLVMJIT.cpp
@@ -852,11 +852,7 @@
 	module->setTargetTriple(LLVM_DEFAULT_TARGET_TRIPLE);
 	module->setDataLayout(JITGlobals::get()->getDataLayout());
 
-	if(REACTOR_ENABLE_MEMORY_SANITIZER_INSTRUMENTATION ||
-	   getPragmaState(MemorySanitizerInstrumentation))
-	{
-		msanInstrumentation = true;
-	}
+	msanInstrumentation = getPragmaState(MemorySanitizerInstrumentation);
 }
 
 void JITBuilder::runPasses()
diff --git a/src/Reactor/Pragma.cpp b/src/Reactor/Pragma.cpp
index 73d5920..38e22ad 100644
--- a/src/Reactor/Pragma.cpp
+++ b/src/Reactor/Pragma.cpp
@@ -30,7 +30,7 @@
 
 struct PragmaState
 {
-	bool memorySanitizerInstrumentation = false;
+	bool memorySanitizerInstrumentation = true;
 	int optimizationLevel = 2;  // Default
 };
 
diff --git a/src/Reactor/Reactor.hpp b/src/Reactor/Reactor.hpp
index 4a68b12..d6a796b 100644
--- a/src/Reactor/Reactor.hpp
+++ b/src/Reactor/Reactor.hpp
@@ -61,12 +61,6 @@
 #	define __has_feature(x) 0
 #endif
 
-// Whether Reactor routine instrumentation is enabled for MSan builds.
-// TODO(b/155148722): Remove when unconditionally instrumenting for all build systems.
-#if !defined REACTOR_ENABLE_MEMORY_SANITIZER_INSTRUMENTATION
-#	define REACTOR_ENABLE_MEMORY_SANITIZER_INSTRUMENTATION 0
-#endif
-
 namespace rr {
 
 struct Caps