diff --git a/compiler-rt/lib/gwp_asan/common.cpp b/compiler-rt/lib/gwp_asan/common.cpp
--- a/compiler-rt/lib/gwp_asan/common.cpp
+++ b/compiler-rt/lib/gwp_asan/common.cpp
@@ -34,6 +34,9 @@
   __builtin_trap();
 }
 
+constexpr size_t AllocationMetadata::kStackFrameStorageBytes;
+constexpr size_t AllocationMetadata::kMaxTraceLengthToCollect;
+
 void AllocationMetadata::RecordAllocation(uintptr_t AllocAddr,
                                           size_t AllocSize) {
   Addr = AllocAddr;
diff --git a/compiler-rt/lib/gwp_asan/crash_handler.cpp b/compiler-rt/lib/gwp_asan/crash_handler.cpp
--- a/compiler-rt/lib/gwp_asan/crash_handler.cpp
+++ b/compiler-rt/lib/gwp_asan/crash_handler.cpp
@@ -10,6 +10,7 @@
 #include "gwp_asan/stack_trace_compressor.h"
 
 #include <assert.h>
+#include <string.h>
 
 using AllocationMetadata = gwp_asan::AllocationMetadata;
 using Error = gwp_asan::Error;
@@ -112,9 +113,15 @@
 size_t __gwp_asan_get_allocation_trace(
     const gwp_asan::AllocationMetadata *AllocationMeta, uintptr_t *Buffer,
     size_t BufferLen) {
-  return gwp_asan::compression::unpack(
+  uintptr_t UncompressedBuffer[AllocationMetadata::kMaxTraceLengthToCollect];
+  size_t UnpackedLength = gwp_asan::compression::unpack(
       AllocationMeta->AllocationTrace.CompressedTrace,
-      AllocationMeta->AllocationTrace.TraceSize, Buffer, BufferLen);
+      AllocationMeta->AllocationTrace.TraceSize, UncompressedBuffer,
+      AllocationMetadata::kMaxTraceLengthToCollect);
+  if (UnpackedLength < BufferLen)
+    BufferLen = UnpackedLength;
+  memcpy(Buffer, UncompressedBuffer, BufferLen * sizeof(*Buffer));
+  return UnpackedLength;
 }
 
 bool __gwp_asan_is_deallocated(
@@ -130,9 +137,15 @@
 size_t __gwp_asan_get_deallocation_trace(
     const gwp_asan::AllocationMetadata *AllocationMeta, uintptr_t *Buffer,
     size_t BufferLen) {
-  return gwp_asan::compression::unpack(
+  uintptr_t UncompressedBuffer[AllocationMetadata::kMaxTraceLengthToCollect];
+  size_t UnpackedLength = gwp_asan::compression::unpack(
       AllocationMeta->DeallocationTrace.CompressedTrace,
-      AllocationMeta->DeallocationTrace.TraceSize, Buffer, BufferLen);
+      AllocationMeta->DeallocationTrace.TraceSize, UncompressedBuffer,
+      AllocationMetadata::kMaxTraceLengthToCollect);
+  if (UnpackedLength < BufferLen)
+    BufferLen = UnpackedLength;
+  memcpy(Buffer, UncompressedBuffer, BufferLen * sizeof(*Buffer));
+  return UnpackedLength;
 }
 
 #ifdef __cplusplus
diff --git a/compiler-rt/lib/gwp_asan/tests/backtrace.cpp b/compiler-rt/lib/gwp_asan/tests/backtrace.cpp
--- a/compiler-rt/lib/gwp_asan/tests/backtrace.cpp
+++ b/compiler-rt/lib/gwp_asan/tests/backtrace.cpp
@@ -8,6 +8,7 @@
 
 #include <string>
 
+#include "gwp_asan/common.h"
 #include "gwp_asan/crash_handler.h"
 #include "gwp_asan/tests/harness.h"
 
@@ -76,9 +77,46 @@
 TEST(Backtrace, ExceedsStorableLength) {
   gwp_asan::AllocationMetadata Meta;
   Meta.AllocationTrace.RecordBacktrace(
-      [](uintptr_t * /* TraceBuffer */, size_t /* Size */) -> size_t {
-        return SIZE_MAX; // Wow, that's big!
+      [](uintptr_t *TraceBuffer, size_t Size) -> size_t {
+        // Need to inintialise the elements that will be packed.
+        memset(TraceBuffer, 0u, Size * sizeof(*TraceBuffer));
+
+        // Indicate that there were more frames, and we just didn't have enough
+        // room to store them.
+        return Size * 2;
+      });
+  // Retrieve a frame from the collected backtrace, make sure it works E2E.
+  uintptr_t TraceOutput;
+  EXPECT_EQ(gwp_asan::AllocationMetadata::kMaxTraceLengthToCollect,
+            __gwp_asan_get_allocation_trace(&Meta, &TraceOutput, 1));
+}
+
+TEST(Backtrace, ExceedsRetrievableAllocLength) {
+  gwp_asan::AllocationMetadata Meta;
+  constexpr size_t kNumFramesToStore = 3u;
+  Meta.AllocationTrace.RecordBacktrace(
+      [](uintptr_t *TraceBuffer, size_t /* Size */) -> size_t {
+        memset(TraceBuffer, kNumFramesToStore,
+               kNumFramesToStore * sizeof(*TraceBuffer));
+        return kNumFramesToStore;
+      });
+  uintptr_t TraceOutput;
+  // Ask for one element, get told that there's `kNumFramesToStore` available.
+  EXPECT_EQ(kNumFramesToStore,
+            __gwp_asan_get_allocation_trace(&Meta, &TraceOutput, 1));
+}
+
+TEST(Backtrace, ExceedsRetrievableDellocLength) {
+  gwp_asan::AllocationMetadata Meta;
+  constexpr size_t kNumFramesToStore = 3u;
+  Meta.DeallocationTrace.RecordBacktrace(
+      [](uintptr_t *TraceBuffer, size_t /* Size */) -> size_t {
+        memset(TraceBuffer, kNumFramesToStore,
+               kNumFramesToStore * sizeof(*TraceBuffer));
+        return kNumFramesToStore;
       });
   uintptr_t TraceOutput;
-  EXPECT_EQ(1u, __gwp_asan_get_allocation_trace(&Meta, &TraceOutput, 1));
+  // Ask for one element, get told that there's `kNumFramesToStore` available.
+  EXPECT_EQ(kNumFramesToStore,
+            __gwp_asan_get_deallocation_trace(&Meta, &TraceOutput, 1));
 }