diff --git a/compiler-rt/lib/sanitizer_common/tests/sanitizer_allocator_test.cpp b/compiler-rt/lib/sanitizer_common/tests/sanitizer_allocator_test.cpp
--- a/compiler-rt/lib/sanitizer_common/tests/sanitizer_allocator_test.cpp
+++ b/compiler-rt/lib/sanitizer_common/tests/sanitizer_allocator_test.cpp
@@ -36,6 +36,17 @@
 #define SKIP_ON_SOLARIS_SPARCV9(x) x
 #endif
 
+// On 64-bit systems with small virtual address spaces (e.g. 39-bit) we can't
+// use size class maps with a large number of classes, as that will make the
+// SizeClassAllocator64 region size too small (< 2^32).
+#if SANITIZER_ANDROID && defined(__aarch64__)
+#define ALLOCATOR64_SMALL_SIZE 1
+#elif SANITIZER_RISCV64
+#define ALLOCATOR64_SMALL_SIZE 1
+#else
+#define ALLOCATOR64_SMALL_SIZE 0
+#endif
+
 // Too slow for debug build
 #if !SANITIZER_DEBUG
 
@@ -53,6 +64,11 @@
 static const uptr kAllocatorSize  = 0x2000000000ULL;
 static const u64 kAddressSpaceSize = 1ULL << 39;
 typedef VeryCompactSizeClassMap SizeClassMap;
+#elif SANITIZER_RISCV64
+const uptr kAllocatorSpace = ~(uptr)0;
+const uptr kAllocatorSize = 0x2000000000ULL;  // 128G.
+static const u64 kAddressSpaceSize = 1ULL << 38;
+typedef VeryDenseSizeClassMap SizeClassMap;
 #else
 static const uptr kAllocatorSpace = 0x700000000000ULL;
 static const uptr kAllocatorSize  = 0x010000000000ULL;  // 1T.
@@ -276,8 +292,7 @@
   TestSizeClassAllocator<Allocator64Dynamic>();
 }
 
-#if !SANITIZER_ANDROID
-//FIXME(kostyak): find values so that those work on Android as well.
+#if !ALLOCATOR64_SMALL_SIZE
 TEST(SanitizerCommon, SizeClassAllocator64Compact) {
   TestSizeClassAllocator<Allocator64Compact>();
 }
@@ -361,7 +376,7 @@
   SizeClassAllocatorMetadataStress<Allocator64Dynamic>();
 }
 
-#if !SANITIZER_ANDROID
+#if !ALLOCATOR64_SMALL_SIZE
 TEST(SanitizerCommon, SizeClassAllocator64CompactMetadataStress) {
   SizeClassAllocatorMetadataStress<Allocator64Compact>();
 }
@@ -408,7 +423,7 @@
   SizeClassAllocatorGetBlockBeginStress<Allocator64Dynamic>(
       1ULL << (SANITIZER_ANDROID ? 31 : 33));
 }
-#if !SANITIZER_ANDROID
+#if !ALLOCATOR64_SMALL_SIZE
 TEST(SanitizerCommon, SizeClassAllocator64CompactGetBlockBegin) {
   SizeClassAllocatorGetBlockBeginStress<Allocator64Compact>(1ULL << 33);
 }
@@ -520,7 +535,7 @@
 
 // Don't test OOM conditions on Win64 because it causes other tests on the same
 // machine to OOM.
-#if SANITIZER_CAN_USE_ALLOCATOR64 && !SANITIZER_WINDOWS64 && !SANITIZER_ANDROID
+#if SANITIZER_CAN_USE_ALLOCATOR64 && !SANITIZER_WINDOWS64
 TEST(SanitizerCommon, SizeClassAllocator64Overflow) {
   Allocator64 a;
   a.Init(kReleaseToOSIntervalNever);
@@ -534,7 +549,8 @@
   uint32_t chunks[kNumChunks];
   bool allocation_failed = false;
   for (int i = 0; i < 1000000; i++) {
-    if (!a.GetFromAllocator(&stats, 52, chunks, kNumChunks)) {
+    uptr class_id = a.kNumClasses - 1;
+    if (!a.GetFromAllocator(&stats, class_id, chunks, kNumChunks)) {
       allocation_failed = true;
       break;
     }
@@ -698,7 +714,7 @@
   TestCombinedAllocator<Allocator64Dynamic>();
 }
 
-#if !SANITIZER_ANDROID
+#if !ALLOCATOR64_SMALL_SIZE
 TEST(SanitizerCommon, CombinedAllocator64Compact) {
   TestCombinedAllocator<Allocator64Compact>();
 }
@@ -759,7 +775,7 @@
   TestSizeClassAllocatorLocalCache<Allocator64Dynamic>();
 }
 
-#if !SANITIZER_ANDROID
+#if !ALLOCATOR64_SMALL_SIZE
 TEST(SanitizerCommon, SizeClassAllocator64CompactLocalCache) {
   TestSizeClassAllocatorLocalCache<Allocator64Compact>();
 }
@@ -1016,8 +1032,8 @@
 
 // Don't test OOM conditions on Win64 because it causes other tests on the same
 // machine to OOM.
-#if SANITIZER_CAN_USE_ALLOCATOR64 && !SANITIZER_WINDOWS64 && !SANITIZER_ANDROID
-typedef __sanitizer::SizeClassMap<3, 4, 8, 38, 128, 16> SpecialSizeClassMap;
+#if SANITIZER_CAN_USE_ALLOCATOR64 && !SANITIZER_WINDOWS64
+typedef __sanitizer::SizeClassMap<2, 22, 22, 34, 128, 16> SpecialSizeClassMap;
 template <typename AddressSpaceViewTy = LocalAddressSpaceView>
 struct AP64_SpecialSizeClassMap {
   static const uptr kSpaceBeg = kAllocatorSpace;
@@ -1044,7 +1060,7 @@
   // ...one man is on a mission to overflow a region with a series of
   // successive allocations.
 
-  const uptr kClassID = 107;
+  const uptr kClassID = kAllocatorSize == ALLOCATOR64_SMALL_SIZE ? 18 : 24;
   const uptr kAllocationSize = SpecialSizeClassMap::Size(kClassID);
   ASSERT_LT(2 * kAllocationSize, kRegionSize);
   ASSERT_GT(3 * kAllocationSize, kRegionSize);
@@ -1052,7 +1068,7 @@
   EXPECT_NE(cache.Allocate(a, kClassID), nullptr);
   EXPECT_EQ(cache.Allocate(a, kClassID), nullptr);
 
-  const uptr Class2 = 100;
+  const uptr Class2 = kAllocatorSize == ALLOCATOR64_SMALL_SIZE ? 15 : 21;
   const uptr Size2 = SpecialSizeClassMap::Size(Class2);
   ASSERT_EQ(Size2 * 8, kRegionSize);
   char *p[7];
@@ -1338,7 +1354,7 @@
   TestReleaseFreeMemoryToOS<Allocator64>();
 }
 
-#if !SANITIZER_ANDROID
+#if !ALLOCATOR64_SMALL_SIZE
 TEST(SanitizerCommon, SizeClassAllocator64CompactReleaseFreeMemoryToOS) {
   TestReleaseFreeMemoryToOS<Allocator64Compact>();
 }
@@ -1346,7 +1362,7 @@
 TEST(SanitizerCommon, SizeClassAllocator64VeryCompactReleaseFreeMemoryToOS) {
   TestReleaseFreeMemoryToOS<Allocator64VeryCompact>();
 }
-#endif  // !SANITIZER_ANDROID
+#endif  // !ALLOCATOR64_SMALL_SIZE
 
 #endif  // SANITIZER_CAN_USE_ALLOCATOR64