diff --git a/lib/ExecutionEngine/JIT/JITMemoryManager.cpp b/lib/ExecutionEngine/JIT/JITMemoryManager.cpp
index 7be6ef8cba9..61bc119d305 100644
--- a/lib/ExecutionEngine/JIT/JITMemoryManager.cpp
+++ b/lib/ExecutionEngine/JIT/JITMemoryManager.cpp
@@ -461,6 +461,9 @@ namespace {
     /// allocateCodeSection - Allocate memory for a code section.
     uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
                                  unsigned SectionID) {
+      // Grow the required block size to account for the block header
+      Size += sizeof(*CurBlock);
+
       // FIXME: Alignement handling.
       FreeRangeHeader* candidateBlock = FreeMemoryList;
       FreeRangeHeader* head = FreeMemoryList;