diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake
--- a/compiler-rt/cmake/config-ix.cmake
+++ b/compiler-rt/cmake/config-ix.cmake
@@ -305,7 +305,7 @@
 else()
   set(ALL_LSAN_SUPPORTED_ARCH ${X86} ${X86_64} ${MIPS64} ${ARM64} ${ARM32} ${PPC64})
 endif()
-set(ALL_MSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64} ${PPC64})
+set(ALL_MSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64} ${PPC64} ${S390X})
 set(ALL_HWASAN_SUPPORTED_ARCH ${X86_64} ${ARM64})
 set(ALL_PROFILE_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${PPC64}
     ${MIPS32} ${MIPS64} ${S390X} ${SPARC} ${SPARCV9})
diff --git a/compiler-rt/lib/msan/msan.h b/compiler-rt/lib/msan/msan.h
--- a/compiler-rt/lib/msan/msan.h
+++ b/compiler-rt/lib/msan/msan.h
@@ -181,6 +181,20 @@
 #define MEM_TO_SHADOW(mem) (LINEARIZE_MEM((mem)) + 0x080000000000ULL)
 #define SHADOW_TO_ORIGIN(shadow) (((uptr)(shadow)) + 0x140000000000ULL)
 
+#elif SANITIZER_LINUX && SANITIZER_S390_64
+const MappingDesc kMemoryLayout[] = {
+    {0x000000000000ULL, 0x040000000000ULL, MappingDesc::APP, "low memory"},
+    {0x040000000000ULL, 0x080000000000ULL, MappingDesc::INVALID, "invalid"},
+    {0x080000000000ULL, 0x180000000000ULL, MappingDesc::SHADOW, "shadow"},
+    {0x180000000000ULL, 0x1C0000000000ULL, MappingDesc::INVALID, "invalid"},
+    {0x1C0000000000ULL, 0x2C0000000000ULL, MappingDesc::ORIGIN, "origin"},
+    {0x2C0000000000ULL, 0x440000000000ULL, MappingDesc::INVALID, "invalid"},
+    {0x440000000000ULL, 0x500000000000ULL, MappingDesc::APP, "high memory"}};
+
+#define MEM_TO_SHADOW(mem) \
+  ((((uptr)(mem)) & ~0xC00000000000ULL) + 0x080000000000ULL)
+#define SHADOW_TO_ORIGIN(shadow) (((uptr)(shadow)) + 0x140000000000ULL)
+
 #elif SANITIZER_FREEBSD && SANITIZER_WORDSIZE == 64
 
 // Low memory: main binary, MAP_32BIT mappings and modules
diff --git a/compiler-rt/lib/msan/msan_allocator.cpp b/compiler-rt/lib/msan/msan_allocator.cpp
--- a/compiler-rt/lib/msan/msan_allocator.cpp
+++ b/compiler-rt/lib/msan/msan_allocator.cpp
@@ -93,6 +93,20 @@
 };
 
 typedef SizeClassAllocator64<AP64> PrimaryAllocator;
+#elif defined(__s390x__)
+static const uptr kMaxAllowedMallocSize = 2UL << 30;  // 2G
+
+struct AP64 {  // Allocator64 parameters. Deliberately using a short name.
+  static const uptr kSpaceBeg = 0x440000000000;
+  static const uptr kSpaceSize = 0x020000000000;  // 2T.
+  static const uptr kMetadataSize = sizeof(Metadata);
+  typedef DefaultSizeClassMap SizeClassMap;
+  typedef MsanMapUnmapCallback MapUnmapCallback;
+  static const uptr kFlags = 0;
+  using AddressSpaceView = LocalAddressSpaceView;
+};
+
+typedef SizeClassAllocator64<AP64> PrimaryAllocator;
 #elif defined(__aarch64__)
 static const uptr kMaxAllowedMallocSize = 2UL << 30;  // 2G
 
diff --git a/compiler-rt/test/msan/backtrace.cpp b/compiler-rt/test/msan/backtrace.cpp
--- a/compiler-rt/test/msan/backtrace.cpp
+++ b/compiler-rt/test/msan/backtrace.cpp
@@ -12,8 +12,14 @@
   int sz = backtrace(buf, sizeof(buf) / sizeof(*buf));
   assert(sz > 0);
   for (int i = 0; i < sz; ++i)
-    if (!buf[i])
+    if (!buf[i]) {
+#if defined(__s390x__)
+      // backtrace() may return a bogus trailing NULL on s390x.
+      if (i == sz - 1)
+        continue;
+#endif
       exit(1);
+    }
   char **s = backtrace_symbols(buf, sz);
   assert(s != 0);
   for (int i = 0; i < sz; ++i)
diff --git a/compiler-rt/test/msan/lit.cfg.py b/compiler-rt/test/msan/lit.cfg.py
--- a/compiler-rt/test/msan/lit.cfg.py
+++ b/compiler-rt/test/msan/lit.cfg.py
@@ -18,6 +18,9 @@
 # Some Msan tests leverage backtrace() which requires libexecinfo on FreeBSD.
 if config.host_os == 'FreeBSD':
   clang_msan_cflags += ["-lexecinfo", "-fPIC"]
+# On SystemZ we need -mbackchain to make the fast unwinder work.
+if config.target_arch == 's390x':
+  clang_msan_cflags.append("-mbackchain")
 clang_msan_cxxflags = config.cxx_mode_flags + clang_msan_cflags
 
 # Flags for KMSAN invocation. This is C-only, we're not interested in C++.
diff --git a/compiler-rt/test/msan/mmap.cpp b/compiler-rt/test/msan/mmap.cpp
--- a/compiler-rt/test/msan/mmap.cpp
+++ b/compiler-rt/test/msan/mmap.cpp
@@ -24,6 +24,9 @@
          addr >= 0xe200000000ULL;
 #elif defined(__powerpc64__)
   return addr < 0x000100000000ULL || addr >= 0x300000000000ULL;
+#elif defined(__s390x__)
+  return addr < 0x040000000000ULL ||
+         (addr >= 0x440000000000ULL && addr < 0x500000000000);
 #elif defined(__aarch64__)
 
   struct AddrMapping {
diff --git a/compiler-rt/test/msan/mmap_below_shadow.cpp b/compiler-rt/test/msan/mmap_below_shadow.cpp
--- a/compiler-rt/test/msan/mmap_below_shadow.cpp
+++ b/compiler-rt/test/msan/mmap_below_shadow.cpp
@@ -27,6 +27,9 @@
 #elif defined (__powerpc64__)
   uintptr_t hint = 0x2f0000000000ULL;
   const uintptr_t app_start = 0x300000000000ULL;
+#elif defined(__s390x__)
+  uintptr_t hint = 0x07f000000000ULL;
+  const uintptr_t app_start = 0x020000000000ULL;
 #elif defined (__aarch64__)
   uintptr_t hint = 0x4f0000000ULL;
   const uintptr_t app_start = 0x7000000000ULL;
diff --git a/compiler-rt/test/msan/param_tls_limit.cpp b/compiler-rt/test/msan/param_tls_limit.cpp
--- a/compiler-rt/test/msan/param_tls_limit.cpp
+++ b/compiler-rt/test/msan/param_tls_limit.cpp
@@ -8,6 +8,12 @@
 // AArch64 fails with:
 // void f801(S<801>): Assertion `__msan_test_shadow(&s, sizeof(s)) == -1' failed
 // XFAIL: aarch64
+// When passing huge structs by value, SystemZ uses pointers, therefore this
+// test in its present form is unfortunately not applicable.
+// ABI says: "A struct or union of any other size <snip>. Replace such an
+// argument by a pointer to the object, or to a copy where necessary to enforce
+// call-by-value semantics."
+// XFAIL: s390x
 
 #include <sanitizer/msan_interface.h>
 #include <assert.h>
diff --git a/compiler-rt/test/msan/strlen_of_shadow.cpp b/compiler-rt/test/msan/strlen_of_shadow.cpp
--- a/compiler-rt/test/msan/strlen_of_shadow.cpp
+++ b/compiler-rt/test/msan/strlen_of_shadow.cpp
@@ -21,6 +21,8 @@
 #define LINEARIZE_MEM(mem) \
   (((uintptr_t)(mem) & ~0x200000000000ULL) ^ 0x100000000000ULL)
   return (char *)(LINEARIZE_MEM(p) + 0x080000000000ULL);
+#elif defined(__s390x__)
+  return (char *)(((uintptr_t)p & ~0xC00000000000ULL) + 0x080000000000ULL);
 #elif defined(__aarch64__)
   return (char *)((uintptr_t)p ^ 0x6000000000ULL);
 #endif