--- a/mozglue/build/arm.cpp
+++ b/mozglue/build/arm.cpp
@@ -8,106 +8,17 @@
 
 #if defined(MOZILLA_ARM_HAVE_CPUID_DETECTION)
 
 // arm.h has parallel #ifs which declare MOZILLA_ARM_HAVE_CPUID_DETECTION.
 // We don't check it here so that we get compile errors if it's defined, but
 // we don't compile one of these detection methods. The detection code here is
 // based on the CPU detection in libtheora.
 
-#  if defined(_MSC_VER)
-//For GetExceptionCode() and EXCEPTION_ILLEGAL_INSTRUCTION.
-#    define WIN32_LEAN_AND_MEAN
-#    define WIN32_EXTRA_LEAN
-#    include <windows.h>
-
-#    if !defined(MOZILLA_PRESUME_EDSP)
-static bool
-check_edsp(void)
-{
-#      if defined(MOZILLA_MAY_SUPPORT_EDSP)
-  __try
-  {
-    //PLD [r13]
-    __emit(0xF5DDF000);
-    return true;
-  }
-  __except(GetExceptionCode()==EXCEPTION_ILLEGAL_INSTRUCTION)
-  {
-    //Ignore exception.
-  }
-#      endif
-  return false;
-}
-#    endif // !MOZILLA_PRESUME_EDSP
-
-#    if !defined(MOZILLA_PRESUME_ARMV6)
-static bool
-check_armv6(void)
-{
-#      if defined(MOZILLA_MAY_SUPPORT_ARMV6)
-  __try
-  {
-    //SHADD8 r3,r3,r3
-    __emit(0xE6333F93);
-    return true;
-  }
-  __except(GetExceptionCode()==EXCEPTION_ILLEGAL_INSTRUCTION)
-  {
-    //Ignore exception.
-  }
-#      endif
-  return false;
-}
-#    endif // !MOZILLA_PRESUME_ARMV6
-
-#    if !defined(MOZILLA_PRESUME_ARMV7)
-static bool
-check_armv7(void)
-{
-#      if defined(MOZILLA_MAY_SUPPORT_ARMV7)
-  __try
-  {
-    // ARMv7 DMB (Data Memory Barrier) for stores (DMB.ST)
-    // The Data Memory Barrier existed before ARMv7 as a
-    // cp15 operation, but ARMv7 introduced a dedicated
-    // instruction, DMB.
-    emit(0xF57FF05E);
-    return true;
-  }
-  __except(GetExceptionCode()==EXCEPTION_ILLEGAL_INSTRUCTION)
-  {
-    //Ignore exception.
-  }
-#      endif
-  return false;
-}
-#    endif // !MOZILLA_PRESUME_ARMV7
-
-#    if !defined(MOZILLA_PRESUME_NEON)
-static bool
-check_neon(void)
-{
-#      if defined(MOZILLA_MAY_SUPPORT_NEON)
-  __try
-  {
-    //VORR q0,q0,q0
-    __emit(0xF2200150);
-    return true;
-  }
-  __except(GetExceptionCode()==EXCEPTION_ILLEGAL_INSTRUCTION)
-  {
-    //Ignore exception.
-  }
-#      endif
-  return false;
-}
-#    endif // !MOZILLA_PRESUME_NEON
-
-#  elif defined(__linux__) || defined(ANDROID)
+#  if defined(__linux__) || defined(ANDROID)
 #    include <stdio.h>
 #    include <stdlib.h>
 #    include <string.h>
 
 enum{
   MOZILLA_HAS_EDSP_FLAG=1,
   MOZILLA_HAS_ARMV6_FLAG=2,
   MOZILLA_HAS_ARMV7_FLAG=4,

--- a/mozglue/build/arm.h
+++ b/mozglue/build/arm.h
@@ -75,33 +75,16 @@
 #    define MOZILLA_PRESUME_NEON 1
 #  endif
 
   // Currently we only have CPU detection for Linux via /proc/cpuinfo
 #  if defined(__linux__) || defined(ANDROID)
 #    define MOZILLA_ARM_HAVE_CPUID_DETECTION 1
 #  endif
 
-#elif defined(_MSC_VER) && defined(_M_ARM)
-
-#  define MOZILLA_ARM_HAVE_CPUID_DETECTION 1
-  // _M_ARM on MSVC has current cpu architecture.
-#  define MOZILLA_ARM_ARCH _M_ARM
-
-  // MSVC only allows external asm for ARM, so we don't have to rely on
-  // compiler support.
-#  define MOZILLA_MAY_SUPPORT_EDSP 1
-#  if defined(HAVE_ARM_SIMD)
-#    define MOZILLA_MAY_SUPPORT_ARMV6 1
-#    define MOZILLA_MAY_SUPPORT_ARMV7 1
-#  endif
-#  if defined(HAVE_ARM_NEON)
-#    define MOZILLA_MAY_SUPPORT_NEON 1
-#  endif
-
 #endif
 
 namespace mozilla {
 
   namespace arm_private {
 #if defined(MOZILLA_ARM_HAVE_CPUID_DETECTION)
 #if !defined(MOZILLA_PRESUME_EDSP)
     extern bool MFBT_DATA edsp_enabled;