diff --git a/compiler/image_writer.cc b/compiler/image_writer.cc
index b1b971f..0b69810 100644
--- a/compiler/image_writer.cc
+++ b/compiler/image_writer.cc
@@ -1542,15 +1542,16 @@
       }
       case kNativeObjectRelocationTypeArtMethodArrayClean:
       case kNativeObjectRelocationTypeArtMethodArrayDirty: {
-        memcpy(dest, pair.first, LengthPrefixedArray<ArtMethod>::ComputeSize(
-            0,
-            ArtMethod::Size(target_ptr_size_),
-            ArtMethod::Alignment(target_ptr_size_)));
+        size_t size = ArtMethod::Size(target_ptr_size_);
+        size_t alignment = ArtMethod::Alignment(target_ptr_size_);
+        memcpy(dest, pair.first, LengthPrefixedArray<ArtMethod>::ComputeSize(0, size, alignment));
+        // Clear padding to avoid non-deterministic data in the image (and placate valgrind).
+        reinterpret_cast<LengthPrefixedArray<ArtMethod>*>(dest)->ClearPadding(size, alignment);
         break;
+      }
       case kNativeObjectRelocationTypeDexCacheArray:
         // Nothing to copy here, everything is done in FixupDexCache().
         break;
-      }
     }
   }
   // Fixup the image method roots.
diff --git a/runtime/base/length_prefixed_array.h b/runtime/base/length_prefixed_array.h
index d632871..8060263 100644
--- a/runtime/base/length_prefixed_array.h
+++ b/runtime/base/length_prefixed_array.h
@@ -18,6 +18,7 @@
 #define ART_RUNTIME_BASE_LENGTH_PREFIXED_ARRAY_H_
 
 #include <stddef.h>  // for offsetof()
+#include <string.h>  // for memset()
 
 #include "stride_iterator.h"
 #include "base/bit_utils.h"
@@ -84,6 +85,13 @@
     size_ = dchecked_integral_cast<uint32_t>(length);
   }
 
+  // Clear the potentially uninitialized padding between the size_ and actual data.
+  void ClearPadding(size_t element_size = sizeof(T), size_t alignment = alignof(T)) {
+    size_t gap_offset = offsetof(LengthPrefixedArray<T>, data);
+    size_t gap_size = OffsetOfElement(0, element_size, alignment) - gap_offset;
+    memset(reinterpret_cast<uint8_t*>(this) + gap_offset, 0, gap_size);
+  }
+
  private:
   T& AtUnchecked(size_t index, size_t element_size, size_t alignment) {
     return *reinterpret_cast<T*>(