diff --git a/compiler-rt/lib/asan/asan_descriptions.cpp b/compiler-rt/lib/asan/asan_descriptions.cpp
--- a/compiler-rt/lib/asan/asan_descriptions.cpp
+++ b/compiler-rt/lib/asan/asan_descriptions.cpp
@@ -48,7 +48,7 @@
     return;
   }
   context->announced = true;
-  InternalScopedString str(1024);
+  InternalScopedString str;
   str.append("Thread %s", AsanThreadIdAndName(context).c_str());
   if (context->parent_tid == kInvalidTid) {
     str.append(" created by unknown thread\n");
@@ -125,7 +125,7 @@
 
 static void PrintHeapChunkAccess(uptr addr, const ChunkAccess &descr) {
   Decorator d;
-  InternalScopedString str(4096);
+  InternalScopedString str;
   str.append("%s", d.Location());
   switch (descr.access_type) {
     case kAccessTypeLeft:
@@ -242,7 +242,7 @@
     else if (addr >= prev_var_end && addr - prev_var_end >= var.beg - addr_end)
       pos_descr = "underflows";
   }
-  InternalScopedString str(1024);
+  InternalScopedString str;
   str.append("    [%zd, %zd)", var.beg, var_end);
   // Render variable name.
   str.append(" '");
@@ -275,7 +275,7 @@
 // Global descriptions
 static void DescribeAddressRelativeToGlobal(uptr addr, uptr access_size,
                                             const __asan_global &g) {
-  InternalScopedString str(4096);
+  InternalScopedString str;
   Decorator d;
   str.append("%s", d.Location());
   if (addr < g.beg) {
diff --git a/compiler-rt/lib/asan/asan_errors.cpp b/compiler-rt/lib/asan/asan_errors.cpp
--- a/compiler-rt/lib/asan/asan_errors.cpp
+++ b/compiler-rt/lib/asan/asan_errors.cpp
@@ -343,7 +343,8 @@
   Report("ERROR: AddressSanitizer: %s (%p):\n", scariness.GetDescription(),
          global1.beg);
   Printf("%s", d.Default());
-  InternalScopedString g1_loc(256), g2_loc(256);
+  InternalScopedString g1_loc;
+  InternalScopedString g2_loc;
   PrintGlobalLocation(&g1_loc, global1);
   PrintGlobalLocation(&g2_loc, global2);
   Printf("  [1] size=%zd '%s' %s\n", global1.size,
@@ -360,7 +361,7 @@
   Report(
       "HINT: if you don't care about these errors you may set "
       "ASAN_OPTIONS=detect_odr_violation=0\n");
-  InternalScopedString error_msg(256);
+  InternalScopedString error_msg;
   error_msg.append("%s: global '%s' at %s", scariness.GetDescription(),
                    MaybeDemangleGlobalName(global1.name), g1_loc.data());
   ReportErrorSummary(error_msg.data());
@@ -554,7 +555,7 @@
   uptr shadow_addr = MemToShadow(addr);
   const uptr n_bytes_per_row = 16;
   uptr aligned_shadow = shadow_addr & ~(n_bytes_per_row - 1);
-  InternalScopedString str(4096 * 8);
+  InternalScopedString str;
   str.append("Shadow bytes around the buggy address:\n");
   for (int i = -5; i <= 5; i++) {
     uptr row_shadow_addr = aligned_shadow + i * n_bytes_per_row;
diff --git a/compiler-rt/lib/asan/asan_fake_stack.cpp b/compiler-rt/lib/asan/asan_fake_stack.cpp
--- a/compiler-rt/lib/asan/asan_fake_stack.cpp
+++ b/compiler-rt/lib/asan/asan_fake_stack.cpp
@@ -65,7 +65,7 @@
 void FakeStack::Destroy(int tid) {
   PoisonAll(0);
   if (Verbosity() >= 2) {
-    InternalScopedString str(kNumberOfSizeClasses * 50);
+    InternalScopedString str;
     for (uptr class_id = 0; class_id < kNumberOfSizeClasses; class_id++)
       str.append("%zd: %zd/%zd; ", class_id, hint_position_[class_id],
                  NumberOfFrames(stack_size_log(), class_id));
diff --git a/compiler-rt/lib/hwasan/hwasan.cpp b/compiler-rt/lib/hwasan/hwasan.cpp
--- a/compiler-rt/lib/hwasan/hwasan.cpp
+++ b/compiler-rt/lib/hwasan/hwasan.cpp
@@ -136,8 +136,6 @@
   Die();
 }
 
-static constexpr uptr kMemoryUsageBufferSize = 4096;
-
 static void HwasanFormatMemoryUsage(InternalScopedString &s) {
   HwasanThreadList &thread_list = hwasanThreadList();
   auto thread_stats = thread_list.GetThreadStats();
@@ -155,6 +153,8 @@
 }
 
 #if SANITIZER_ANDROID
+static constexpr uptr kMemoryUsageBufferSize = 4096;
+
 static char *memory_usage_buffer = nullptr;
 
 static void InitMemoryUsage() {
@@ -171,7 +171,7 @@
     return;
   if (!memory_usage_buffer)
     InitMemoryUsage();
-  InternalScopedString s(kMemoryUsageBufferSize);
+  InternalScopedString s;
   HwasanFormatMemoryUsage(s);
   internal_strncpy(memory_usage_buffer, s.data(), kMemoryUsageBufferSize - 1);
   memory_usage_buffer[kMemoryUsageBufferSize - 1] = '\0';
@@ -493,7 +493,7 @@
 }
 
 void __hwasan_print_memory_usage() {
-  InternalScopedString s(kMemoryUsageBufferSize);
+  InternalScopedString s;
   HwasanFormatMemoryUsage(s);
   Printf("%s\n", s.data());
 }
diff --git a/compiler-rt/lib/hwasan/hwasan_report.cpp b/compiler-rt/lib/hwasan/hwasan_report.cpp
--- a/compiler-rt/lib/hwasan/hwasan_report.cpp
+++ b/compiler-rt/lib/hwasan/hwasan_report.cpp
@@ -224,7 +224,7 @@
 
   // We didn't find any locals. Most likely we don't have symbols, so dump
   // the information that we have for offline analysis.
-  InternalScopedString frame_desc(GetPageSizeCached() * 2);
+  InternalScopedString frame_desc;
   Printf("Previously allocated frames:\n");
   for (uptr i = 0; i < frames; i++) {
     const uptr *record_addr = &(*sa)[i];
@@ -459,7 +459,7 @@
       RoundDownTo(reinterpret_cast<uptr>(tag_ptr), row_len));
   tag_t *beg_row = center_row_beg - row_len * (num_rows / 2);
   tag_t *end_row = center_row_beg + row_len * ((num_rows + 1) / 2);
-  InternalScopedString s(GetPageSizeCached() * 8);
+  InternalScopedString s;
   for (tag_t *row = beg_row; row < end_row; row += row_len) {
     s.append("%s", row == center_row_beg ? "=>" : "  ");
     s.append("%p:", row);
@@ -547,7 +547,7 @@
     GetStackTraceFromId(chunk.GetAllocStackId()).Print();
   }
 
-  InternalScopedString s(GetPageSizeCached() * 8);
+  InternalScopedString s;
   CHECK_GT(tail_size, 0U);
   CHECK_LT(tail_size, kShadowAlignment);
   u8 *tail = reinterpret_cast<u8*>(untagged_addr + orig_size);
diff --git a/compiler-rt/lib/lsan/lsan_common.cpp b/compiler-rt/lib/lsan/lsan_common.cpp
--- a/compiler-rt/lib/lsan/lsan_common.cpp
+++ b/compiler-rt/lib/lsan/lsan_common.cpp
@@ -895,7 +895,7 @@
       bytes += leaks_[i].total_size;
       allocations += leaks_[i].hit_count;
   }
-  InternalScopedString summary(kMaxSummaryLength);
+  InternalScopedString summary;
   summary.append("%zu byte(s) leaked in %zu allocation(s).", bytes,
                  allocations);
   ReportErrorSummary(summary.data());
diff --git a/compiler-rt/lib/memprof/memprof_descriptions.cpp b/compiler-rt/lib/memprof/memprof_descriptions.cpp
--- a/compiler-rt/lib/memprof/memprof_descriptions.cpp
+++ b/compiler-rt/lib/memprof/memprof_descriptions.cpp
@@ -48,7 +48,7 @@
     return;
   }
   context->announced = true;
-  InternalScopedString str(1024);
+  InternalScopedString str;
   str.append("Thread %s", MemprofThreadIdAndName(context).c_str());
   if (context->parent_tid == kInvalidTid) {
     str.append(" created by unknown thread\n");
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common.h b/compiler-rt/lib/sanitizer_common/sanitizer_common.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common.h
@@ -44,7 +44,7 @@
 
 const uptr kMaxThreadStackSize = 1 << 30;  // 1Gb
 
-static const uptr kErrorMessageBufferSize = 1 << 16;
+const uptr kErrorMessageBufferSize = 1 << 16;
 
 // Denotes fake PC values that come from JIT/JAVA/etc.
 // For such PC values __tsan_symbolize_external_ex() will be called.
@@ -344,8 +344,6 @@
 void SetAlternateSignalStack();
 void UnsetAlternateSignalStack();
 
-// We don't want a summary too long.
-const int kMaxSummaryLength = 1024;
 // Construct a one-line string:
 //   SUMMARY: SanitizerToolName: error_message
 // and pass it to __sanitizer_report_error_summary.
@@ -594,14 +592,12 @@
 
 class InternalScopedString {
  public:
-  explicit InternalScopedString(uptr max_length)
-      : buffer_(max_length), length_(0) {
-    buffer_[0] = '\0';
-  }
-  uptr length() const { return length_; }
+  explicit InternalScopedString() : buffer_(1) { buffer_[0] = '\0'; }
+
+  uptr length() const { return buffer_.size() - 1; }
   void clear() {
+    buffer_.resize(1);
     buffer_[0] = '\0';
-    length_ = 0;
   }
   void append(const char *format, ...);
   const char *data() const { return buffer_.data(); }
@@ -609,7 +605,6 @@
 
  private:
   InternalMmapVector<char> buffer_;
-  uptr length_;
 };
 
 template <class T>
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_common.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common.cpp
@@ -87,7 +87,7 @@
 void ReportErrorSummary(const char *error_message, const char *alt_tool_name) {
   if (!common_flags()->print_summary)
     return;
-  InternalScopedString buff(kMaxSummaryLength);
+  InternalScopedString buff;
   buff.append("SUMMARY: %s: %s",
               alt_tool_name ? alt_tool_name : SanitizerToolName, error_message);
   __sanitizer_report_error_summary(buff.data());
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp
@@ -92,7 +92,7 @@
 #endif
 
 void WriteToSyslog(const char *msg) {
-  InternalScopedString msg_copy(kErrorMessageBufferSize);
+  InternalScopedString msg_copy;
   msg_copy.append("%s", msg);
   const char *p = msg_copy.data();
 
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
@@ -606,7 +606,7 @@
   }
 
   if (info->dlpi_name) {
-    InternalScopedString module_name(kMaxPathLength);
+    InternalScopedString module_name;
     module_name.append("%s", info->dlpi_name);
     return AddModuleSegments(module_name.data(), info, data->modules);
   }
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_malloc_mac.inc b/compiler-rt/lib/sanitizer_common/sanitizer_malloc_mac.inc
--- a/compiler-rt/lib/sanitizer_common/sanitizer_malloc_mac.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_malloc_mac.inc
@@ -124,7 +124,7 @@
   // bytes.
   size_t buflen =
       sizeof(COMMON_MALLOC_ZONE_NAME "-") + (name ? internal_strlen(name) : 0);
-  InternalScopedString new_name(buflen);
+  InternalScopedString new_name;
   if (name && zone->introspect == sanitizer_zone.introspect) {
     new_name.append(COMMON_MALLOC_ZONE_NAME "-%s", name);
     name = new_name.data();
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp
@@ -346,13 +346,24 @@
 
 FORMAT(2, 3)
 void InternalScopedString::append(const char *format, ...) {
-  CHECK_LT(length_, buffer_.size());
-  va_list args;
-  va_start(args, format);
-  VSNPrintf(buffer_.data() + length_, buffer_.size() - length_, format, args);
-  va_end(args);
-  length_ += internal_strlen(data() + length_);
-  CHECK_LT(length_, buffer_.size());
+  uptr prev_len = length();
+
+  while (true) {
+    buffer_.resize(buffer_.capacity());
+
+    va_list args;
+    va_start(args, format);
+    uptr sz = VSNPrintf(buffer_.data() + prev_len, buffer_.size() - prev_len,
+                        format, args);
+    va_end(args);
+    if (sz < buffer_.size() - prev_len) {
+      buffer_.resize(prev_len + sz + 1);
+      break;
+    }
+
+    buffer_.reserve(buffer_.capacity() * 2);
+  }
+  CHECK_EQ(buffer_[length()], '\0');
 }
 
 } // namespace __sanitizer
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace_libcdep.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace_libcdep.cpp
@@ -23,8 +23,8 @@
     Printf("    <empty stack>\n\n");
     return;
   }
-  InternalScopedString frame_desc(GetPageSizeCached() * 2);
-  InternalScopedString dedup_token(GetPageSizeCached());
+  InternalScopedString frame_desc;
+  InternalScopedString dedup_token;
   int dedup_frames = common_flags()->dedup_token_length;
   bool symbolize = RenderNeedsSymbolization(common_flags()->stack_trace_format);
   uptr frame_num = 0;
@@ -125,7 +125,7 @@
     out_buf[out_buf_size - 1] = 0;
     return;
   }
-  InternalScopedString frame_desc(GetPageSizeCached());
+  InternalScopedString frame_desc;
   uptr frame_num = 0;
   // Reserve one byte for the final 0.
   char *out_end = out_buf + out_buf_size - 1;
@@ -156,7 +156,7 @@
   out_buf[0] = 0;
   DataInfo DI;
   if (!Symbolizer::GetOrInit()->SymbolizeData(data_addr, &DI)) return;
-  InternalScopedString data_desc(GetPageSizeCached());
+  InternalScopedString data_desc;
   RenderData(&data_desc, fmt, &DI, common_flags()->strip_path_prefix);
   internal_strncpy(out_buf, data_desc.data(), out_buf_size);
   out_buf[out_buf_size - 1] = 0;
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_report.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_report.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_report.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_report.cpp
@@ -31,7 +31,7 @@
 void ReportErrorSummary(const char *error_type, const AddressInfo &info,
                         const char *alt_tool_name) {
   if (!common_flags()->print_summary) return;
-  InternalScopedString buff(kMaxSummaryLength);
+  InternalScopedString buff;
   buff.append("%s ", error_type);
   RenderFrame(&buff, "%L %F", 0, info.address, &info,
               common_flags()->symbolize_vs_style,
@@ -150,7 +150,7 @@
 static void MaybeDumpInstructionBytes(uptr pc) {
   if (!common_flags()->dump_instruction_bytes || (pc < GetPageSizeCached()))
     return;
-  InternalScopedString str(1024);
+  InternalScopedString str;
   str.append("First 16 instruction bytes at pc: ");
   if (IsAccessibleMemoryRange(pc, 16)) {
     for (int i = 0; i < 16; ++i) {
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_win.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_win.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_win.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_win.cpp
@@ -224,7 +224,7 @@
   // Compute the command line. Wrap double quotes around everything.
   const char *argv[kArgVMax];
   GetArgV(path_, argv);
-  InternalScopedString command_line(kMaxPathLength * 3);
+  InternalScopedString command_line;
   for (int i = 0; argv[i]; i++) {
     const char *arg = argv[i];
     int arglen = internal_strlen(arg);
diff --git a/compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp b/compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp
--- a/compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp
+++ b/compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp
@@ -350,7 +350,7 @@
 }
 
 TEST(SanitizerCommon, InternalScopedString) {
-  InternalScopedString str(10);
+  InternalScopedString str;
   EXPECT_EQ(0U, str.length());
   EXPECT_STREQ("", str.data());
 
@@ -364,20 +364,37 @@
   EXPECT_STREQ("foo1234", str.data());
 
   str.append("%d", x);
-  EXPECT_EQ(9U, str.length());
-  EXPECT_STREQ("foo123412", str.data());
+  EXPECT_EQ(11U, str.length());
+  EXPECT_STREQ("foo12341234", str.data());
 
   str.clear();
   EXPECT_EQ(0U, str.length());
   EXPECT_STREQ("", str.data());
+}
 
-  str.append("0123456789");
-  EXPECT_EQ(9U, str.length());
-  EXPECT_STREQ("012345678", str.data());
+TEST(SanitizerCommon, InternalScopedStringLarge) {
+  InternalScopedString str;
+  std::string expected;
+  for (int i = 0; i < 1000; ++i) {
+    std::string append(i, 'a' + i % 26);
+    expected += append;
+    str.append(append.c_str());
+    EXPECT_EQ(expected, str.data());
+  }
+}
+
+TEST(SanitizerCommon, InternalScopedStringLargeFormat) {
+  InternalScopedString str;
+  std::string expected;
+  for (int i = 0; i < 1000; ++i) {
+    std::string append(i, 'a' + i % 26);
+    expected += append;
+    str.append("%s", append.c_str());
+    EXPECT_EQ(expected, str.data());
+  }
 }
 
-#if SANITIZER_LINUX || SANITIZER_FREEBSD || \
-  SANITIZER_MAC || SANITIZER_IOS
+#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_MAC || SANITIZER_IOS
 TEST(SanitizerCommon, GetRandom) {
   u8 buffer_1[32], buffer_2[32];
   for (bool blocking : { false, true }) {
diff --git a/compiler-rt/lib/sanitizer_common/tests/sanitizer_stacktrace_printer_test.cpp b/compiler-rt/lib/sanitizer_common/tests/sanitizer_stacktrace_printer_test.cpp
--- a/compiler-rt/lib/sanitizer_common/tests/sanitizer_stacktrace_printer_test.cpp
+++ b/compiler-rt/lib/sanitizer_common/tests/sanitizer_stacktrace_printer_test.cpp
@@ -16,7 +16,7 @@
 namespace __sanitizer {
 
 TEST(SanitizerStacktracePrinter, RenderSourceLocation) {
-  InternalScopedString str(128);
+  InternalScopedString str;
   RenderSourceLocation(&str, "/dir/file.cc", 10, 5, false, "");
   EXPECT_STREQ("/dir/file.cc:10:5", str.data());
 
@@ -50,7 +50,7 @@
 }
 
 TEST(SanitizerStacktracePrinter, RenderModuleLocation) {
-  InternalScopedString str(128);
+  InternalScopedString str;
   RenderModuleLocation(&str, "/dir/exe", 0x123, kModuleArchUnknown, "");
   EXPECT_STREQ("(/dir/exe+0x123)", str.data());
 
@@ -76,7 +76,7 @@
   info.file = internal_strdup("/path/to/my/source");
   info.line = 10;
   info.column = 5;
-  InternalScopedString str(256);
+  InternalScopedString str;
 
   // Dump all the AddressInfo fields.
   RenderFrame(&str,
diff --git a/compiler-rt/lib/tsan/rtl/tsan_report.cpp b/compiler-rt/lib/tsan/rtl/tsan_report.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_report.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_report.cpp
@@ -127,7 +127,7 @@
   }
   SymbolizedStack *frame = ent->frames;
   for (int i = 0; frame && frame->info.address; frame = frame->next, i++) {
-    InternalScopedString res(2 * GetPageSizeCached());
+    InternalScopedString res;
     RenderFrame(&res, common_flags()->stack_trace_format, i,
                 frame->info.address, &frame->info,
                 common_flags()->symbolize_vs_style,
diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp b/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp
@@ -167,7 +167,7 @@
     } else if (internal_strcmp(flags()->profile_memory, "stderr") == 0) {
       mprof_fd = 2;
     } else {
-      InternalScopedString filename(kMaxPathLength);
+      InternalScopedString filename;
       filename.append("%s.%d", flags()->profile_memory, (int)internal_getpid());
       fd_t fd = OpenFile(filename.data(), WrOnly);
       if (fd == kInvalidFd) {
diff --git a/compiler-rt/lib/ubsan/ubsan_diag.cpp b/compiler-rt/lib/ubsan/ubsan_diag.cpp
--- a/compiler-rt/lib/ubsan/ubsan_diag.cpp
+++ b/compiler-rt/lib/ubsan/ubsan_diag.cpp
@@ -278,7 +278,7 @@
   }
 
   // Emit data.
-  InternalScopedString Buffer(1024);
+  InternalScopedString Buffer;
   for (uptr P = Min; P != Max; ++P) {
     unsigned char C = *reinterpret_cast<const unsigned char*>(P);
     Buffer.append("%s%02x", (P % 8 == 0) ? "  " : " ", C);
@@ -346,7 +346,7 @@
   // All diagnostics should be printed under report mutex.
   ScopedReport::CheckLocked();
   Decorator Decor;
-  InternalScopedString Buffer(1024);
+  InternalScopedString Buffer;
 
   // Prepare a report that a monitor process can inspect.
   if (Level == DL_Error) {
diff --git a/compiler-rt/lib/ubsan/ubsan_monitor.cpp b/compiler-rt/lib/ubsan/ubsan_monitor.cpp
--- a/compiler-rt/lib/ubsan/ubsan_monitor.cpp
+++ b/compiler-rt/lib/ubsan/ubsan_monitor.cpp
@@ -17,7 +17,7 @@
 UndefinedBehaviorReport::UndefinedBehaviorReport(const char *IssueKind,
                                                  Location &Loc,
                                                  InternalScopedString &Msg)
-    : IssueKind(IssueKind), Loc(Loc), Buffer(Msg.length() + 1) {
+    : IssueKind(IssueKind), Loc(Loc) {
   // We have the common sanitizer reporting lock, so it's safe to register a
   // new UB report.
   RegisterUndefinedBehaviorReport(this);