Index: llvm/trunk/include/llvm/ExecutionEngine/SectionMemoryManager.h
===================================================================
--- llvm/trunk/include/llvm/ExecutionEngine/SectionMemoryManager.h
+++ llvm/trunk/include/llvm/ExecutionEngine/SectionMemoryManager.h
@@ -84,8 +84,23 @@
 
 private:
   struct MemoryGroup {
-      SmallVector<sys::MemoryBlock, 16> AllocatedMem;
+      // PendingMem contains all allocated memory blocks
+      // which have not yet had their permissions set. Note
+      // that this tracks memory blocks that have been given to
+      // this memory manager by the system, not those
+      // given out to the user. In particular, the memory manager
+      // will give out subblocks of these MemoryBlocks in response
+      // to user requests. We track which subblocks have not beeen
+      // given out yet in `FreeMem`.
+      SmallVector<sys::MemoryBlock, 16> PendingMem;
       SmallVector<sys::MemoryBlock, 16> FreeMem;
+
+      // All allocated memory blocks that have had their permissions
+      // set (i.e. that have been finalized). Because of this, we may
+      // not give out subblocks of this memory to the user anymore,
+      // even if those subblocks have not been previously given out.
+      SmallVector<sys::MemoryBlock, 16> AllocatedMem;
+
       sys::MemoryBlock Near;
   };
 
Index: llvm/trunk/lib/ExecutionEngine/SectionMemoryManager.cpp
===================================================================
--- llvm/trunk/lib/ExecutionEngine/SectionMemoryManager.cpp
+++ llvm/trunk/lib/ExecutionEngine/SectionMemoryManager.cpp
@@ -83,7 +83,7 @@
   // Save this address as the basis for our next request
   MemGroup.Near = MB;
 
-  MemGroup.AllocatedMem.push_back(MB);
+  MemGroup.PendingMem.push_back(MB);
   Addr = (uintptr_t)MB.base();
   uintptr_t EndOfBlock = Addr + MB.size();
 
@@ -138,6 +138,14 @@
   // relocations) will get to the data cache but not to the instruction cache.
   invalidateInstructionCache();
 
+  // Now, remember that we have successfully applied the permissions to avoid
+  // having to apply them again.
+  CodeMem.AllocatedMem.append(CodeMem.PendingMem.begin(),CodeMem.PendingMem.end());
+  CodeMem.PendingMem.clear();
+
+  RODataMem.AllocatedMem.append(RODataMem.PendingMem.begin(),RODataMem.PendingMem.end());
+  RODataMem.PendingMem.clear();
+
   return false;
 }
 
@@ -145,7 +153,7 @@
 SectionMemoryManager::applyMemoryGroupPermissions(MemoryGroup &MemGroup,
                                                   unsigned Permissions) {
 
-  for (sys::MemoryBlock &MB : MemGroup.AllocatedMem)
+  for (sys::MemoryBlock &MB : MemGroup.PendingMem)
     if (std::error_code EC = sys::Memory::protectMappedMemory(MB, Permissions))
       return EC;
 
@@ -153,14 +161,17 @@
 }
 
 void SectionMemoryManager::invalidateInstructionCache() {
-  for (sys::MemoryBlock &Block : CodeMem.AllocatedMem)
+  for (sys::MemoryBlock &Block : CodeMem.PendingMem)
     sys::Memory::InvalidateInstructionCache(Block.base(), Block.size());
 }
 
 SectionMemoryManager::~SectionMemoryManager() {
-  for (MemoryGroup *Group : {&CodeMem, &RWDataMem, &RODataMem})
+  for (MemoryGroup *Group : {&CodeMem, &RWDataMem, &RODataMem}) {
     for (sys::MemoryBlock &Block : Group->AllocatedMem)
       sys::Memory::releaseMappedMemory(Block);
+    for (sys::MemoryBlock &Block : Group->PendingMem)
+      sys::Memory::releaseMappedMemory(Block);
+  }
 }
 
 } // namespace llvm