Index: cmake/config-ix.cmake
===================================================================
--- cmake/config-ix.cmake
+++ cmake/config-ix.cmake
@@ -179,7 +179,7 @@
 # by other sanitizers (even if they build into dummy object files).
 filter_available_targets(LSAN_COMMON_SUPPORTED_ARCH
   ${SANITIZER_COMMON_SUPPORTED_ARCH})
-filter_available_targets(MSAN_SUPPORTED_ARCH x86_64 mips64 mips64el)
+filter_available_targets(MSAN_SUPPORTED_ARCH i386 x86_64 mips64 mips64el)
 filter_available_targets(PROFILE_SUPPORTED_ARCH x86_64 i386 i686 arm mips mips64
   mipsel mips64el aarch64 powerpc64 powerpc64le)
 filter_available_targets(TSAN_SUPPORTED_ARCH x86_64)
Index: lib/msan/msan.h
===================================================================
--- lib/msan/msan.h
+++ lib/msan/msan.h
@@ -25,7 +25,14 @@
 # define MSAN_REPLACE_OPERATORS_NEW_AND_DELETE 1
 #endif
 
-#if defined(__mips64)
+#if defined(__i386__)
+#define MEM_TO_SHADOW(mem)       (((uptr)mem) & ~0x80000000UL)
+#define SHADOW_TO_ORIGIN(shadow) (((uptr)shadow) + 0x40000000UL)
+#define MEM_TO_ORIGIN(mem)       (SHADOW_TO_ORIGIN(MEM_TO_SHADOW(mem)))
+#define MEM_IS_APP(mem)          ((uptr)mem >= 0xc0000000UL)
+#define MEM_IS_SHADOW(mem) \
+  ((uptr)mem >= 0x40000000UL && (uptr)mem <= 0x80000000UL)
+#elif defined(__mips64)
 #define MEM_TO_SHADOW(mem)       (((uptr)mem) & ~0x4000000000ULL)
 #define SHADOW_TO_ORIGIN(shadow) (((uptr)shadow) + 0x2000000000ULL)
 #define MEM_TO_ORIGIN(mem)       (SHADOW_TO_ORIGIN(MEM_TO_SHADOW(mem)))
Index: lib/msan/msan_allocator.cc
===================================================================
--- lib/msan/msan_allocator.cc
+++ lib/msan/msan_allocator.cc
@@ -40,7 +40,16 @@
   }
 };
 
-#if defined(__mips64)
+#if defined (__i386__)
+  static const uptr kMaxAllowedMallocSize = 3UL << 30;
+  static const uptr kRegionSizeLog = 20;
+  static const uptr kNumRegions = SANITIZER_MMAP_RANGE_SIZE >> kRegionSizeLog;
+  typedef FlatByteMap<kNumRegions> ByteMap;
+  typedef CompactSizeClassMap SizeClassMap;
+  typedef SizeClassAllocator32<0, SANITIZER_MMAP_RANGE_SIZE, sizeof(Metadata),
+                               SizeClassMap, kRegionSizeLog, ByteMap,
+                               MsanMapUnmapCallback> PrimaryAllocator;
+#elif defined(__mips64)
   static const uptr kMaxAllowedMallocSize = 2UL << 30;
   static const uptr kRegionSizeLog = 20;
   static const uptr kNumRegions = SANITIZER_MMAP_RANGE_SIZE >> kRegionSizeLog;
Index: lib/msan/msan_linux.cc
===================================================================
--- lib/msan/msan_linux.cc
+++ lib/msan/msan_linux.cc
@@ -35,7 +35,10 @@
 
 namespace __msan {
 
-#if defined(__mips64)
+#if defined(__i386__)
+static const uptr kMemBeg     = 0xc0000000;
+static const uptr kMemEnd     = 0xffffffff;
+#elif defined(__mips64)
 static const uptr kMemBeg     = 0xe000000000;
 static const uptr kMemEnd     = 0xffffffffff;
 #elif defined(__x86_64__)
Index: lib/sanitizer_common/sanitizer_platform_interceptors.h
===================================================================
--- lib/sanitizer_common/sanitizer_platform_interceptors.h
+++ lib/sanitizer_common/sanitizer_platform_interceptors.h
@@ -168,7 +168,8 @@
 #define SANITIZER_INTERCEPT_ETHER_HOST SI_MAC || SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_ETHER_R SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_SHMCTL \
-  ((SI_FREEBSD || SI_LINUX_NOT_ANDROID) && SANITIZER_WORDSIZE == 64)
+  ((SI_FREEBSD || SI_LINUX_NOT_ANDROID) && \
+  (SANITIZER_WORDSIZE == 64 || defined(__i386__)))
 #define SANITIZER_INTERCEPT_RANDOM_R SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_PTHREAD_ATTR_GET SI_NOT_WINDOWS
 #define SANITIZER_INTERCEPT_PTHREAD_ATTR_GETINHERITSCHED \