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
@@ -324,7 +324,7 @@
 else()
   set(ALL_LSAN_SUPPORTED_ARCH ${X86} ${X86_64} ${MIPS64} ${ARM64} ${ARM32} ${PPC64} ${S390X} ${RISCV64})
 endif()
-set(ALL_MSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64} ${PPC64} ${S390X})
+set(ALL_MSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64} ${PPC64} ${S390X} ${RISCV64})
 set(ALL_HWASAN_SUPPORTED_ARCH ${X86_64} ${ARM64})
 set(ALL_MEMPROF_SUPPORTED_ARCH ${X86_64})
 set(ALL_PROFILE_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${PPC32} ${PPC64}
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
@@ -158,6 +158,32 @@
 # define MEM_TO_SHADOW(mem) ((uptr)mem ^ 0x6000000000ULL)
 # define SHADOW_TO_ORIGIN(shadow) (((uptr)(shadow)) + 0x1000000000ULL)
 
+#elif SANITIZER_LINUX && SANITIZER_RISCV64
+
+// RISCV64 mapping:
+// - 0x0000000000-0x0100000000: Program own segments
+// - 0x2aaaaaa000-0x2eaaaaa000: PIE program segments
+// - 0x3e00000000-0x4000000000: libraries segments.
+const MappingDesc kMemoryLayout[] = {
+    {0x000000000000ULL, 0x000100000000ULL, MappingDesc::APP, "app-1"},
+    {0x000100000000ULL, 0x000aaaaaa000ULL, MappingDesc::INVALID, "invalid"},
+    {0x000aaaaaa000ULL, 0x000eaaaaa000ULL, MappingDesc::SHADOW, "shadow-2"},
+    {0x000eaaaaa000ULL, 0x0012aaaaa000ULL, MappingDesc::ORIGIN, "origin-2"},
+    {0x0012aaaaa000ULL, 0x001e00000000ULL, MappingDesc::INVALID, "invalid"},
+    {0x001e00000000ULL, 0x002000000000ULL, MappingDesc::SHADOW, "shadow-3"},
+    {0x002000000000ULL, 0x002100000000ULL, MappingDesc::SHADOW, "shadow-1"},
+    {0x002100000000ULL, 0x002200000000ULL, MappingDesc::INVALID, "invalid"},
+    {0x002200000000ULL, 0x002400000000ULL, MappingDesc::ORIGIN, "origin-3"},
+    {0x002400000000ULL, 0x002500000000ULL, MappingDesc::ORIGIN, "origin-1"},
+    {0x002500000000ULL, 0x002aaaaaa000ULL, MappingDesc::INVALID, "invalid"},
+    {0x002aaaaaa000ULL, 0x002eaaaaa000ULL, MappingDesc::APP, "app-2"},
+    {0x002eaaaaa000ULL, 0x003e00000000ULL, MappingDesc::INVALID, "invalid"},
+    {0x003e00000000ULL, 0x004000000000ULL, MappingDesc::APP, "app-3"},
+};
+
+#define MEM_TO_SHADOW(mem) ((uptr)mem ^ (0x2000000000ULL))
+#define SHADOW_TO_ORIGIN(shadow) (((uptr)(shadow)) + 0x0400000000ULL)
+
 #elif SANITIZER_LINUX && SANITIZER_PPC64
 const MappingDesc kMemoryLayout[] = {
     {0x000000000000ULL, 0x000200000000ULL, MappingDesc::APP, "low memory"},
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
@@ -110,6 +110,20 @@
 #elif defined(__aarch64__)
 static const uptr kMaxAllowedMallocSize = 2UL << 30;  // 2G
 
+struct AP32 {
+  static const uptr kSpaceBeg = 0;
+  static const u64 kSpaceSize = SANITIZER_MMAP_RANGE_SIZE;
+  static const uptr kMetadataSize = sizeof(Metadata);
+  typedef __sanitizer::CompactSizeClassMap SizeClassMap;
+  static const uptr kRegionSizeLog = 20;
+  using AddressSpaceView = LocalAddressSpaceView;
+  typedef MsanMapUnmapCallback MapUnmapCallback;
+  static const uptr kFlags = 0;
+};
+typedef SizeClassAllocator32<AP32> PrimaryAllocator;
+#elif SANITIZER_RISCV64
+static const uptr kMaxAllowedMallocSize = 2UL << 30;
+
 struct AP32 {
   static const uptr kSpaceBeg = 0;
   static const u64 kSpaceSize = SANITIZER_MMAP_RANGE_SIZE;
diff --git a/compiler-rt/test/msan/allocator_mapping.cpp b/compiler-rt/test/msan/allocator_mapping.cpp
--- a/compiler-rt/test/msan/allocator_mapping.cpp
+++ b/compiler-rt/test/msan/allocator_mapping.cpp
@@ -8,7 +8,7 @@
 // This test only makes sense for the 64-bit allocator. The 32-bit allocator
 // does not have a fixed mapping. Exclude platforms that use the 32-bit
 // allocator.
-// UNSUPPORTED: target-is-mips64,target-is-mips64el,aarch64
+// UNSUPPORTED: target-is-mips64,target-is-mips64el,aarch64,riscv64
 
 #include <assert.h>
 #include <stdio.h>
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
@@ -27,6 +27,10 @@
 #elif defined(__s390x__)
   return addr < 0x040000000000ULL ||
          (addr >= 0x440000000000ULL && addr < 0x500000000000);
+#elif defined(__riscv) && (__riscv_xlen == 64)
+  return (addr < 0x000100000000ULL) ||
+         (addr >= 0x002aaaaaa000ULL && addr < 0x002eaaaaa000ULL) ||
+         (addr >= 0x003e00000000ULL && addr < 0x004000000000ULL);
 #elif defined(__aarch64__)
 
   struct AddrMapping {
@@ -62,6 +66,8 @@
   // Large enough to quickly exhaust the entire address space.
 #if defined(__mips64) || defined(__aarch64__)
   const size_t kMapSize = 0x100000000ULL;
+#elif defined(__riscv) && (__riscv_xlen == 64)
+  const size_t kMapSize = 0x80000000ULL;
 #else
   const size_t kMapSize = 0x1000000000ULL;
 #endif
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
@@ -33,6 +33,9 @@
 #elif defined (__aarch64__)
   uintptr_t hint = 0x4f0000000ULL;
   const uintptr_t app_start = 0x7000000000ULL;
+#elif defined(__riscv) && (__riscv_xlen == 64)
+  uintptr_t hint = 0x000a00000000ULL;
+  const uintptr_t app_start = 0x000000000000ULL;
 #endif
   uintptr_t p = (uintptr_t)mmap(
       (void *)hint, 4096, PROT_WRITE,
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
@@ -25,6 +25,8 @@
   return (char *)(((uintptr_t)p & ~0xC00000000000ULL) + 0x080000000000ULL);
 #elif defined(__aarch64__)
   return (char *)((uintptr_t)p ^ 0x6000000000ULL);
+#elif defined(__riscv) && (__riscv_xlen == 64)
+  return (char *)((uintptr_t)p ^ 0x2000000000ULL);
 #endif
 }
 
diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -416,6 +416,14 @@
   0x01000000000,   // OriginBase
 };
 
+// riscv64 Linux
+static const MemoryMapParams Linux_RISCV64_MemoryMapParams = {
+    0,             // AndMask (not used)
+    0x02000000000, // XorMask
+    0,             // ShadowBase (not used)
+    0x00400000000, // OriginBase
+};
+
 // i386 FreeBSD
 static const MemoryMapParams FreeBSD_I386_MemoryMapParams = {
   0x000180000000,  // AndMask
@@ -465,6 +473,11 @@
   &Linux_AArch64_MemoryMapParams,
 };
 
+static const PlatformMemoryMapParams Linux_RISCV_MemoryMapParams = {
+    nullptr,
+    &Linux_RISCV64_MemoryMapParams,
+};
+
 static const PlatformMemoryMapParams FreeBSD_X86_MemoryMapParams = {
   &FreeBSD_I386_MemoryMapParams,
   &FreeBSD_X86_64_MemoryMapParams,
@@ -959,6 +972,9 @@
           case Triple::aarch64_be:
             MapParams = Linux_ARM_MemoryMapParams.bits64;
             break;
+          case Triple::riscv64:
+            MapParams = Linux_RISCV_MemoryMapParams.bits64;
+            break;
           default:
             report_fatal_error("unsupported architecture");
         }