diff --git a/llvm/examples/OrcV2Examples/LLJITWithCustomObjectLinkingLayer/LLJITWithCustomObjectLinkingLayer.cpp b/llvm/examples/OrcV2Examples/LLJITWithCustomObjectLinkingLayer/LLJITWithCustomObjectLinkingLayer.cpp
index a2bdbcbb08ad05..907dc83f463337 100644
--- a/llvm/examples/OrcV2Examples/LLJITWithCustomObjectLinkingLayer/LLJITWithCustomObjectLinkingLayer.cpp
+++ b/llvm/examples/OrcV2Examples/LLJITWithCustomObjectLinkingLayer/LLJITWithCustomObjectLinkingLayer.cpp
@@ -47,7 +47,7 @@ int main(int argc, char *argv[]) {
           .setObjectLinkingLayerCreator(
               [&](ExecutionSession &ES, const Triple &TT) {
                 return std::make_unique<ObjectLinkingLayer>(
-                    ES, std::make_unique<jitlink::InProcessMemoryManager>());
+                    ES, ExitOnErr(jitlink::InProcessMemoryManager::Create()));
               })
           .create());
 
diff --git a/llvm/examples/OrcV2Examples/LLJITWithObjectLinkingLayerPlugin/LLJITWithObjectLinkingLayerPlugin.cpp b/llvm/examples/OrcV2Examples/LLJITWithObjectLinkingLayerPlugin/LLJITWithObjectLinkingLayerPlugin.cpp
index 7bfc93c02989e1..2215e2507db3e5 100644
--- a/llvm/examples/OrcV2Examples/LLJITWithObjectLinkingLayerPlugin/LLJITWithObjectLinkingLayerPlugin.cpp
+++ b/llvm/examples/OrcV2Examples/LLJITWithObjectLinkingLayerPlugin/LLJITWithObjectLinkingLayerPlugin.cpp
@@ -209,7 +209,7 @@ int main(int argc, char *argv[]) {
               [&](ExecutionSession &ES, const Triple &TT) {
                 // Create ObjectLinkingLayer.
                 auto ObjLinkingLayer = std::make_unique<ObjectLinkingLayer>(
-                    ES, std::make_unique<jitlink::InProcessMemoryManager>());
+                    ES, ExitOnErr(jitlink::InProcessMemoryManager::Create()));
                 // Add an instance of our plugin.
                 ObjLinkingLayer->addPlugin(std::make_unique<MyPlugin>());
                 return ObjLinkingLayer;
diff --git a/llvm/include/llvm/ExecutionEngine/JITLink/JITLink.h b/llvm/include/llvm/ExecutionEngine/JITLink/JITLink.h
index 3bd9d6c9798342..9d4b61e15c2ed1 100644
--- a/llvm/include/llvm/ExecutionEngine/JITLink/JITLink.h
+++ b/llvm/include/llvm/ExecutionEngine/JITLink/JITLink.h
@@ -13,19 +13,19 @@
 #ifndef LLVM_EXECUTIONENGINE_JITLINK_JITLINK_H
 #define LLVM_EXECUTIONENGINE_JITLINK_JITLINK_H
 
-#include "JITLinkMemoryManager.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h"
+#include "llvm/ExecutionEngine/JITLink/MemoryFlags.h"
 #include "llvm/ExecutionEngine/JITSymbol.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/MathExtras.h"
-#include "llvm/Support/Memory.h"
 #include "llvm/Support/MemoryBuffer.h"
 
 #include <map>
@@ -225,7 +225,7 @@ class Block : public Addressable {
 
   /// Get the content for this block. Block must not be a zero-fill block.
   ArrayRef<char> getContent() const {
-    assert(Data && "Section does not contain content");
+    assert(Data && "Block does not contain content");
     return ArrayRef<char>(Data, Size);
   }
 
@@ -233,6 +233,7 @@ class Block : public Addressable {
   /// Caller is responsible for ensuring the underlying bytes are not
   /// deallocated while pointed to by this block.
   void setContent(ArrayRef<char> Content) {
+    assert(Content.data() && "Setting null content");
     Data = Content.data();
     Size = Content.size();
     ContentMutable = false;
@@ -251,6 +252,7 @@ class Block : public Addressable {
   /// to call this on a block with immutable content -- consider using
   /// getMutableContent instead.
   MutableArrayRef<char> getAlreadyMutableContent() {
+    assert(Data && "Block does not contain content");
     assert(ContentMutable && "Content is not mutable");
     return MutableArrayRef<char>(const_cast<char *>(Data), Size);
   }
@@ -260,6 +262,7 @@ class Block : public Addressable {
   /// The caller is responsible for ensuring that the memory pointed to by
   /// MutableContent is not deallocated while pointed to by this block.
   void setMutableContent(MutableArrayRef<char> MutableContent) {
+    assert(MutableContent.data() && "Setting null content");
     Data = MutableContent.data();
     Size = MutableContent.size();
     ContentMutable = true;
@@ -295,6 +298,7 @@ class Block : public Addressable {
   /// Add an edge to this block.
   void addEdge(Edge::Kind K, Edge::OffsetT Offset, Symbol &Target,
                Edge::AddendT Addend) {
+    assert(!isZeroFill() && "Adding edge to zero-fill block?");
     Edges.push_back(Edge(K, Offset, Target, Addend));
   }
 
@@ -640,8 +644,7 @@ class Section {
   friend class LinkGraph;
 
 private:
-  Section(StringRef Name, sys::Memory::ProtectionFlags Prot,
-          SectionOrdinal SecOrdinal)
+  Section(StringRef Name, MemProt Prot, SectionOrdinal SecOrdinal)
       : Name(Name), Prot(Prot), SecOrdinal(SecOrdinal) {}
 
   using SymbolSet = DenseSet<Symbol *>;
@@ -666,12 +669,16 @@ class Section {
   StringRef getName() const { return Name; }
 
   /// Returns the protection flags for this section.
-  sys::Memory::ProtectionFlags getProtectionFlags() const { return Prot; }
+  MemProt getMemProt() const { return Prot; }
 
   /// Set the protection flags for this section.
-  void setProtectionFlags(sys::Memory::ProtectionFlags Prot) {
-    this->Prot = Prot;
-  }
+  void setMemProt(MemProt Prot) { this->Prot = Prot; }
+
+  /// Get the deallocation policy for this section.
+  MemDeallocPolicy getMemDeallocPolicy() const { return MDP; }
+
+  /// Set the deallocation policy for this section.
+  void setMemDeallocPolicy(MemDeallocPolicy MDP) { this->MDP = MDP; }
 
   /// Returns the ordinal for this section.
   SectionOrdinal getOrdinal() const { return SecOrdinal; }
@@ -686,6 +693,7 @@ class Section {
     return make_range(Blocks.begin(), Blocks.end());
   }
 
+  /// Returns the number of blocks in this section.
   BlockSet::size_type blocks_size() const { return Blocks.size(); }
 
   /// Returns an iterator over the symbols defined in this section.
@@ -734,7 +742,8 @@ class Section {
   }
 
   StringRef Name;
-  sys::Memory::ProtectionFlags Prot;
+  MemProt Prot;
+  MemDeallocPolicy MDP = MemDeallocPolicy::Standard;
   SectionOrdinal SecOrdinal = 0;
   BlockSet Blocks;
   SymbolSet Symbols;
@@ -916,6 +925,11 @@ class LinkGraph {
       : Name(std::move(Name)), TT(TT), PointerSize(PointerSize),
         Endianness(Endianness), GetEdgeKindName(std::move(GetEdgeKindName)) {}
 
+  LinkGraph(const LinkGraph &) = delete;
+  LinkGraph &operator=(const LinkGraph &) = delete;
+  LinkGraph(LinkGraph &&) = delete;
+  LinkGraph &operator=(LinkGraph &&) = delete;
+
   /// Returns the name of this graph (usually the name of the original
   /// underlying MemoryBuffer).
   const std::string &getName() const { return Name; }
@@ -962,7 +976,7 @@ class LinkGraph {
   }
 
   /// Create a section with the given name, protection flags, and alignment.
-  Section &createSection(StringRef Name, sys::Memory::ProtectionFlags Prot) {
+  Section &createSection(StringRef Name, MemProt Prot) {
     assert(llvm::find_if(Sections,
                          [&](std::unique_ptr<Section> &Sec) {
                            return Sec->getName() == Name;
@@ -1350,6 +1364,13 @@ class LinkGraph {
     Sections.erase(I);
   }
 
+  /// Accessor for the AllocActions object for this graph. This can be used to
+  /// register allocation action calls prior to finalization.
+  ///
+  /// Accessing this object after finalization will result in undefined
+  /// behavior.
+  JITLinkMemoryManager::AllocActions &allocActions() { return AAs; }
+
   /// Dump the graph.
   void dump(raw_ostream &OS);
 
@@ -1366,6 +1387,7 @@ class LinkGraph {
   SectionList Sections;
   ExternalSymbolSet ExternalSymbols;
   ExternalSymbolSet AbsoluteSymbols;
+  JITLinkMemoryManager::AllocActions AAs;
 };
 
 inline MutableArrayRef<char> Block::getMutableContent(LinkGraph &G) {
@@ -1655,8 +1677,7 @@ class JITLinkContext {
   /// finalized (i.e. emitted to memory and memory permissions set). If all of
   /// this objects dependencies have also been finalized then the code is ready
   /// to run.
-  virtual void
-  notifyFinalized(std::unique_ptr<JITLinkMemoryManager::Allocation> A) = 0;
+  virtual void notifyFinalized(JITLinkMemoryManager::FinalizedAlloc Alloc) = 0;
 
   /// Called by JITLink prior to linking to determine whether default passes for
   /// the target should be added. The default implementation returns true.
diff --git a/llvm/include/llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h b/llvm/include/llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h
index cee7d6b09c485f..2cb676259a4505 100644
--- a/llvm/include/llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h
+++ b/llvm/include/llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h
@@ -13,106 +13,408 @@
 #ifndef LLVM_EXECUTIONENGINE_JITLINK_JITLINKMEMORYMANAGER_H
 #define LLVM_EXECUTIONENGINE_JITLINK_JITLINKMEMORYMANAGER_H
 
-#include "llvm/ADT/DenseMap.h"
 #include "llvm/ExecutionEngine/JITLink/JITLinkDylib.h"
+#include "llvm/ExecutionEngine/JITLink/MemoryFlags.h"
 #include "llvm/ExecutionEngine/JITSymbol.h"
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MSVCErrorWorkarounds.h"
 #include "llvm/Support/Memory.h"
+#include "llvm/Support/RecyclingAllocator.h"
 
 #include <cstdint>
 #include <future>
+#include <mutex>
 
 namespace llvm {
 namespace jitlink {
 
+class Block;
+class LinkGraph;
+class Section;
+
 /// Manages allocations of JIT memory.
 ///
 /// Instances of this class may be accessed concurrently from multiple threads
 /// and their implemetations should include any necessary synchronization.
 class JITLinkMemoryManager {
 public:
-  using ProtectionFlags = sys::Memory::ProtectionFlags;
+  /// Represents a call to a graph-memory-management support function in the
+  /// executor.
+  ///
+  /// Support functions are called as:
+  ///
+  ///   auto *Result =
+  ///       ((char*(*)(const void*, size_t))FnAddr)(
+  ///           (const void*)CtxAddr, (size_t)CtxSize)
+  ///
+  /// A null result is interpreted as success.
+  ///
+  /// A non-null result is interpreted as a heap-allocated string containing
+  /// an error message to report to the allocator (the allocator's
+  /// executor-side implementation code is responsible for freeing the error
+  /// string).
+  struct AllocActionCall {
+    JITTargetAddress FnAddr = 0;
+    JITTargetAddress CtxAddr = 0;
+    JITTargetAddress CtxSize = 0;
+  };
+
+  /// A pair of AllocActionCalls, one to be run at finalization time, one to be
+  /// run at deallocation time.
+  ///
+  /// AllocActionCallPairs should be constructed for paired operations (e.g.
+  /// __register_ehframe and __deregister_ehframe for eh-frame registration).
+  /// See comments for AllocActions for execution ordering.
+  ///
+  /// For unpaired operations one or the other member can be left unused, as
+  /// AllocationActionCalls with an FnAddr of zero will be skipped.
+  struct AllocActionCallPair {
+    AllocActionCall Finalize;
+    AllocActionCall Dealloc;
+  };
+
+  /// A vector of allocation actions to be run for this allocation.
+  ///
+  /// Finalize allocations will be run in order at finalize time. Dealloc
+  /// actions will be run in reverse order at deallocation time.
+  using AllocActions = std::vector<AllocActionCallPair>;
+
+  /// Represents a finalized allocation.
+  ///
+  /// Finalized allocations must be passed to the
+  /// JITLinkMemoryManager:deallocate method prior to being destroyed.
+  ///
+  /// The interpretation of the Address associated with the finalized allocation
+  /// is up to the memory manager implementation. Common options are using the
+  /// base address of the allocation, or the address of a memory management
+  /// object that tracks the allocation.
+  class FinalizedAlloc {
+    friend class JITLinkMemoryManager;
 
-  class SegmentRequest {
   public:
-    SegmentRequest() = default;
-    SegmentRequest(uint64_t Alignment, size_t ContentSize,
-                   uint64_t ZeroFillSize)
-        : Alignment(Alignment), ContentSize(ContentSize),
-          ZeroFillSize(ZeroFillSize) {
-      assert(isPowerOf2_32(Alignment) && "Alignment must be power of 2");
+    static constexpr JITTargetAddress InvalidAddr = ~JITTargetAddress(0);
+
+    FinalizedAlloc() = default;
+    explicit FinalizedAlloc(JITTargetAddress A) : A(A) {
+      assert(A != 0 && "Explicitly creating an invalid allocation?");
+    }
+    FinalizedAlloc(const FinalizedAlloc &) = delete;
+    FinalizedAlloc(FinalizedAlloc &&Other) : A(Other.A) {
+      Other.A = InvalidAddr;
+    }
+    FinalizedAlloc &operator=(const FinalizedAlloc &) = delete;
+    FinalizedAlloc &operator=(FinalizedAlloc &&Other) {
+      assert(A == InvalidAddr &&
+             "Cannot overwrite active finalized allocation");
+      std::swap(A, Other.A);
+      return *this;
     }
-    uint64_t getAlignment() const { return Alignment; }
-    size_t getContentSize() const { return ContentSize; }
-    uint64_t getZeroFillSize() const { return ZeroFillSize; }
+    ~FinalizedAlloc() {
+      assert(A == InvalidAddr && "Finalized allocation was not deallocated");
+    }
+
+    /// FinalizedAllocs convert to false for default-constructed, and
+    /// true otherwise. Default-constructed allocs need not be deallocated.
+    explicit operator bool() const { return A != InvalidAddr; }
+
+    /// Returns the address associated with this finalized allocation.
+    /// The allocation is unmodified.
+    JITTargetAddress getAddress() const { return A; }
+
+    /// Returns the address associated with this finalized allocation and
+    /// resets this object to the default state.
+    /// This should only be used by allocators when deallocating memory.
+    JITTargetAddress release() {
+      JITTargetAddress Tmp = A;
+      A = InvalidAddr;
+      return Tmp;
+    }
+
   private:
-    uint64_t Alignment = 0;
-    size_t ContentSize = 0;
-    uint64_t ZeroFillSize = 0;
+    JITTargetAddress A = InvalidAddr;
   };
 
-  using SegmentsRequestMap = DenseMap<unsigned, SegmentRequest>;
-
-  /// Represents an allocation created by the memory manager.
+  /// Represents an allocation which has not been finalized yet.
   ///
-  /// An allocation object is responsible for allocating and owning jit-linker
-  /// working and target memory, and for transfering from working to target
-  /// memory.
+  /// InFlightAllocs manage both executor memory allocations and working
+  /// memory allocations.
   ///
-  class Allocation {
+  /// On finalization, the InFlightAlloc should transfer the content of
+  /// working memory into executor memory, apply memory protections, and
+  /// run any finalization functions.
+  ///
+  /// Working memory should be kept alive at least until one of the following
+  /// happens: (1) the InFlightAlloc instance is destroyed, (2) the
+  /// InFlightAlloc is abandoned, (3) finalized target memory is destroyed.
+  ///
+  /// If abandon is called then working memory and executor memory should both
+  /// be freed.
+  class InFlightAlloc {
   public:
-    using FinalizeContinuation = std::function<void(Error)>;
-
-    virtual ~Allocation();
+    using OnFinalizedFunction = unique_function<void(Expected<FinalizedAlloc>)>;
+    using OnAbandonedFunction = unique_function<void(Error)>;
 
-    /// Should return the address of linker working memory for the segment with
-    /// the given protection flags.
-    virtual MutableArrayRef<char> getWorkingMemory(ProtectionFlags Seg) = 0;
+    virtual ~InFlightAlloc();
 
-    /// Should return the final address in the target process where the segment
-    /// will reside.
-    virtual JITTargetAddress getTargetMemory(ProtectionFlags Seg) = 0;
+    /// Called prior to finalization if the allocation should be abandoned.
+    virtual void abandon(OnAbandonedFunction OnAbandoned) = 0;
 
-    /// Should transfer from working memory to target memory, and release
-    /// working memory.
-    virtual void finalizeAsync(FinalizeContinuation OnFinalize) = 0;
+    /// Called to transfer working memory to the target and apply finalization.
+    virtual void finalize(OnFinalizedFunction OnFinalized) = 0;
 
-    /// Calls finalizeAsync and waits for completion.
-    Error finalize() {
-      std::promise<MSVCPError> FinalizeResultP;
+    /// Synchronous convenience version of finalize.
+    Expected<FinalizedAlloc> finalize() {
+      std::promise<MSVCPExpected<FinalizedAlloc>> FinalizeResultP;
       auto FinalizeResultF = FinalizeResultP.get_future();
-      finalizeAsync(
-          [&](Error Err) { FinalizeResultP.set_value(std::move(Err)); });
+      finalize([&](Expected<FinalizedAlloc> Result) {
+        FinalizeResultP.set_value(std::move(Result));
+      });
       return FinalizeResultF.get();
     }
-
-    /// Should deallocate target memory.
-    virtual Error deallocate() = 0;
   };
 
+  /// Typedef for the argument to be passed to OnAllocatedFunction.
+  using AllocResult = Expected<std::unique_ptr<InFlightAlloc>>;
+
+  /// Called when allocation has been completed.
+  using OnAllocatedFunction = unique_function<void(AllocResult)>;
+
+  /// Called when deallocation has completed.
+  using OnDeallocatedFunction = unique_function<void(Error)>;
+
   virtual ~JITLinkMemoryManager();
 
-  /// Create an Allocation object.
+  /// Start the allocation process.
+  ///
+  /// If the initial allocation is successful then the OnAllocated function will
+  /// be called with a std::unique_ptr<InFlightAlloc> value. If the assocation
+  /// is unsuccessful then the OnAllocated function will be called with an
+  /// Error.
+  virtual void allocate(const JITLinkDylib *JD, LinkGraph &G,
+                        OnAllocatedFunction OnAllocated) = 0;
+
+  /// Convenience function for blocking allocation.
+  AllocResult allocate(const JITLinkDylib *JD, LinkGraph &G) {
+    std::promise<MSVCPExpected<std::unique_ptr<InFlightAlloc>>> AllocResultP;
+    auto AllocResultF = AllocResultP.get_future();
+    allocate(JD, G, [&](AllocResult Alloc) {
+      AllocResultP.set_value(std::move(Alloc));
+    });
+    return AllocResultF.get();
+  }
+
+  /// Deallocate a list of allocation objects.
+  ///
+  /// Dealloc actions will be run in reverse order (from the end of the vector
+  /// to the start).
+  virtual void deallocate(std::vector<FinalizedAlloc> Allocs,
+                          OnDeallocatedFunction OnDeallocated) = 0;
+
+  /// Convenience function for deallocation of a single alloc.
+  void deallocate(FinalizedAlloc Alloc, OnDeallocatedFunction OnDeallocated) {
+    std::vector<FinalizedAlloc> Allocs;
+    Allocs.push_back(std::move(Alloc));
+    deallocate(std::move(Allocs), std::move(OnDeallocated));
+  }
+
+  /// Convenience function for blocking deallocation.
+  Error deallocate(std::vector<FinalizedAlloc> Allocs) {
+    std::promise<MSVCPError> DeallocResultP;
+    auto DeallocResultF = DeallocResultP.get_future();
+    deallocate(std::move(Allocs),
+               [&](Error Err) { DeallocResultP.set_value(std::move(Err)); });
+    return DeallocResultF.get();
+  }
+
+  /// Convenience function for blocking deallocation of a single alloc.
+  Error deallocate(FinalizedAlloc Alloc) {
+    std::vector<FinalizedAlloc> Allocs;
+    Allocs.push_back(std::move(Alloc));
+    return deallocate(std::move(Allocs));
+  }
+};
+
+/// BasicLayout simplifies the implementation of JITLinkMemoryManagers.
+///
+/// BasicLayout groups Sections into Segments based on their memory protection
+/// and deallocation policies. JITLinkMemoryManagers can construct a BasicLayout
+/// from a Graph, and then assign working memory and addresses to each of the
+/// Segments. These addreses will be mapped back onto the Graph blocks in
+/// the apply method.
+class BasicLayout {
+public:
+  /// The Alignment, ContentSize and ZeroFillSize of each segment will be
+  /// pre-filled from the Graph. Clients must set the Addr and WorkingMem fields
+  /// prior to calling apply.
+  class Segment {
+    friend class BasicLayout;
+
+  public:
+    Align Alignment;
+    size_t ContentSize = 0;
+    uint64_t ZeroFillSize = 0;
+    JITTargetAddress Addr = 0;
+    char *WorkingMem;
+
+  private:
+    size_t NextWorkingMemOffset = 0;
+    std::vector<Block *> ContentBlocks, ZeroFillBlocks;
+  };
+
+  /// A convenience class that further groups segments based on memory
+  /// deallocation policy. This allows clients to make two slab allocations:
+  /// one for all standard segments, and one for all finalize segments.
+  struct ContiguousPageBasedLayoutSizes {
+    uint64_t StandardSegs = 0;
+    uint64_t FinalizeSegs = 0;
+
+    uint64_t total() const { return StandardSegs + FinalizeSegs; }
+  };
+
+private:
+  using SegmentMap = AllocGroupSmallMap<Segment>;
+
+public:
+  BasicLayout(LinkGraph &G);
+
+  /// Return a reference to the graph this allocation was created from.
+  LinkGraph &getGraph() { return G; }
+
+  /// Returns the total number of required to allocate all segments (with each
+  /// segment padded out to page size) for all standard segments, and all
+  /// finalize segments.
   ///
-  /// The JD argument represents the target JITLinkDylib, and can be used by
-  /// JITLinkMemoryManager implementers to manage per-dylib allocation pools
-  /// (e.g. one pre-reserved address space slab per dylib to ensure that all
-  /// allocations for the dylib are within a certain range). The JD argument
-  /// may be null (representing an allocation not associated with any
-  /// JITDylib.
+  /// This is a convenience function for the common case where the segments will
+  /// be allocated contiguously.
   ///
-  /// The request argument describes the segment sizes and permisssions being
-  /// requested.
-  virtual Expected<std::unique_ptr<Allocation>>
-  allocate(const JITLinkDylib *JD, const SegmentsRequestMap &Request) = 0;
+  /// This function will return an error if any segment has an alignment that
+  /// is higher than a page.
+  Expected<ContiguousPageBasedLayoutSizes>
+  getContiguousPageBasedLayoutSizes(uint64_t PageSize);
+
+  /// Returns an iterator over the segments of the layout.
+  iterator_range<SegmentMap::iterator> segments() {
+    return {Segments.begin(), Segments.end()};
+  }
+
+  /// Apply the layout to the graph.
+  Error apply();
+
+  /// Returns a reference to the AllocActions in the graph.
+  /// This convenience function saves callers from having to #include
+  /// LinkGraph.h if all they need are allocation actions.
+  JITLinkMemoryManager::AllocActions &graphAllocActions();
+
+private:
+  LinkGraph &G;
+  SegmentMap Segments;
+};
+
+/// A utility class for making simple allocations using JITLinkMemoryManager.
+///
+/// SimpleSegementAlloc takes a mapping of AllocGroups to Segments and uses
+/// this to create a LinkGraph with one Section (containing one Block) per
+/// Segment. Clients can obtain a pointer to the working memory and executor
+/// address of that block using the Segment's AllocGroup. Once memory has been
+/// populated, clients can call finalize to finalize the memory.
+class SimpleSegmentAlloc {
+public:
+  /// Describes a segment to be allocated.
+  struct Segment {
+    Segment() = default;
+    Segment(size_t ContentSize, Align ContentAlign)
+        : ContentSize(ContentSize), ContentAlign(ContentAlign) {}
+
+    size_t ContentSize = 0;
+    Align ContentAlign;
+  };
+
+  /// Describes the segment working memory and executor address.
+  struct SegmentInfo {
+    JITTargetAddress Addr = 0;
+    MutableArrayRef<char> WorkingMem;
+  };
+
+  using SegmentMap = AllocGroupSmallMap<Segment>;
+
+  using OnCreatedFunction = unique_function<void(Expected<SimpleSegmentAlloc>)>;
+
+  using OnFinalizedFunction =
+      JITLinkMemoryManager::InFlightAlloc::OnFinalizedFunction;
+
+  static void Create(JITLinkMemoryManager &MemMgr, const JITLinkDylib *JD,
+                     SegmentMap Segments, OnCreatedFunction OnCreated);
+
+  static Expected<SimpleSegmentAlloc> Create(JITLinkMemoryManager &MemMgr,
+                                             const JITLinkDylib *JD,
+                                             SegmentMap Segments);
+
+  SimpleSegmentAlloc(SimpleSegmentAlloc &&);
+  SimpleSegmentAlloc &operator=(SimpleSegmentAlloc &&);
+  ~SimpleSegmentAlloc();
+
+  /// Returns the SegmentInfo for the given group.
+  SegmentInfo getSegInfo(AllocGroup AG);
+
+  /// Finalize all groups (async version).
+  void finalize(OnFinalizedFunction OnFinalized) {
+    Alloc->finalize(std::move(OnFinalized));
+  }
+
+  /// Finalize all groups.
+  Expected<JITLinkMemoryManager::FinalizedAlloc> finalize() {
+    return Alloc->finalize();
+  }
+
+private:
+  SimpleSegmentAlloc(
+      std::unique_ptr<LinkGraph> G, AllocGroupSmallMap<Block *> ContentBlocks,
+      std::unique_ptr<JITLinkMemoryManager::InFlightAlloc> Alloc);
+
+  std::unique_ptr<LinkGraph> G;
+  AllocGroupSmallMap<Block *> ContentBlocks;
+  std::unique_ptr<JITLinkMemoryManager::InFlightAlloc> Alloc;
 };
 
 /// A JITLinkMemoryManager that allocates in-process memory.
 class InProcessMemoryManager : public JITLinkMemoryManager {
 public:
-  Expected<std::unique_ptr<Allocation>>
-  allocate(const JITLinkDylib *JD, const SegmentsRequestMap &Request) override;
+  class IPInFlightAlloc;
+
+  /// Attempts to auto-detect the host page size.
+  static Expected<std::unique_ptr<InProcessMemoryManager>> Create();
+
+  /// Create an instance using the given page size.
+  InProcessMemoryManager(uint64_t PageSize) : PageSize(PageSize) {}
+
+  void allocate(const JITLinkDylib *JD, LinkGraph &G,
+                OnAllocatedFunction OnAllocated) override;
+
+  // Use overloads from base class.
+  using JITLinkMemoryManager::allocate;
+
+  void deallocate(std::vector<FinalizedAlloc> Alloc,
+                  OnDeallocatedFunction OnDeallocated) override;
+
+  // Use overloads from base class.
+  using JITLinkMemoryManager::deallocate;
+
+private:
+  // FIXME: Use an in-place array instead of a vector for DeallocActions.
+  //        There shouldn't need to be a heap alloc for this.
+  struct FinalizedAllocInfo {
+    sys::MemoryBlock StandardSegments;
+    std::vector<AllocActionCall> DeallocActions;
+  };
+
+  FinalizedAlloc
+  createFinalizedAlloc(sys::MemoryBlock StandardSegments,
+                       std::vector<AllocActionCall> DeallocActions);
+
+  uint64_t PageSize;
+  std::mutex FinalizedAllocsMutex;
+  RecyclingAllocator<BumpPtrAllocator, FinalizedAllocInfo> FinalizedAllocInfos;
 };
 
 } // end namespace jitlink
diff --git a/llvm/include/llvm/ExecutionEngine/JITLink/MemoryFlags.h b/llvm/include/llvm/ExecutionEngine/JITLink/MemoryFlags.h
new file mode 100644
index 00000000000000..8fdce93ebc564f
--- /dev/null
+++ b/llvm/include/llvm/ExecutionEngine/JITLink/MemoryFlags.h
@@ -0,0 +1,225 @@
+//===-------- MemoryFlags.h - Memory allocation flags -----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Defines types and operations related to memory protection and allocation
+// lifetimes.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTIONENGINE_JITLINK_MEMORYFLAGS_H
+#define LLVM_EXECUTIONENGINE_JITLINK_MEMORYFLAGS_H
+
+#include "llvm/ADT/BitmaskEnum.h"
+#include "llvm/ADT/DenseMapInfo.h"
+#include "llvm/Support/Memory.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace llvm {
+namespace jitlink {
+
+/// Describes Read/Write/Exec permissions for memory.
+enum class MemProt {
+  None = 0,
+  Read = 1U << 0,
+  Write = 1U << 1,
+  Exec = 1U << 2,
+  LLVM_MARK_AS_BITMASK_ENUM(/* LargestValue = */ Exec)
+};
+
+/// Print a MemProt as an RWX triple.
+raw_ostream &operator<<(raw_ostream &OS, MemProt MP);
+
+/// Convert a MemProt value to a corresponding sys::Memory::ProtectionFlags
+/// value.
+inline sys::Memory::ProtectionFlags toSysMemoryProtectionFlags(MemProt MP) {
+  std::underlying_type_t<sys::Memory::ProtectionFlags> PF = 0;
+  if ((MP & MemProt::Read) != MemProt::None)
+    PF |= sys::Memory::MF_READ;
+  if ((MP & MemProt::Write) != MemProt::None)
+    PF |= sys::Memory::MF_WRITE;
+  if ((MP & MemProt::Exec) != MemProt::None)
+    PF |= sys::Memory::MF_EXEC;
+  return static_cast<sys::Memory::ProtectionFlags>(PF);
+}
+
+/// Convert a sys::Memory::ProtectionFlags value to a corresponding MemProt
+/// value.
+inline MemProt fromSysMemoryProtectionFlags(sys::Memory::ProtectionFlags PF) {
+  MemProt MP = MemProt::None;
+  if (PF & sys::Memory::MF_READ)
+    MP |= MemProt::Read;
+  if (PF & sys::Memory::MF_WRITE)
+    MP |= MemProt::Write;
+  if (PF & sys::Memory::MF_EXEC)
+    MP |= MemProt::None;
+  return MP;
+}
+
+/// Describes a memory deallocation policy for memory to be allocated by a
+/// JITLinkMemoryManager.
+///
+/// All memory allocated by a call to JITLinkMemoryManager::allocate should be
+/// deallocated if a call is made to
+/// JITLinkMemoryManager::InFlightAllocation::abandon. The policies below apply
+/// to finalized allocations.
+enum class MemDeallocPolicy {
+  /// Standard memory should be deallocated when the deallocate method is called
+  /// for the finalized allocation.
+  Standard,
+
+  /// Finalize memory should be overwritten and then deallocated after all
+  /// finalization functions have been run.
+  Finalize
+};
+
+/// Print a MemDeallocPolicy.
+raw_ostream &operator<<(raw_ostream &OS, MemDeallocPolicy MDP);
+
+/// A pair of memory protections and allocation policies.
+///
+/// Optimized for use as a small map key.
+class AllocGroup {
+  friend struct llvm::DenseMapInfo<AllocGroup>;
+
+  using underlying_type = uint8_t;
+  static constexpr unsigned BitsForProt = 3;
+  static constexpr unsigned BitsForDeallocPolicy = 1;
+  static constexpr unsigned MaxIdentifiers =
+      1U << (BitsForProt + BitsForDeallocPolicy);
+
+public:
+  static constexpr unsigned NumGroups = MaxIdentifiers;
+
+  /// Create a default AllocGroup. No memory protections, standard
+  /// deallocation policy.
+  AllocGroup() = default;
+
+  /// Create an AllocGroup from a MemProt only -- uses
+  /// MemoryDeallocationPolicy::Standard.
+  AllocGroup(MemProt MP) : Id(static_cast<underlying_type>(MP)) {}
+
+  /// Create an AllocGroup from a MemProt and a MemoryDeallocationPolicy.
+  AllocGroup(MemProt MP, MemDeallocPolicy MDP)
+      : Id(static_cast<underlying_type>(MP) |
+           (static_cast<underlying_type>(MDP) << BitsForProt)) {}
+
+  /// Returns the MemProt for this group.
+  MemProt getMemProt() const {
+    return static_cast<MemProt>(Id & ((1U << BitsForProt) - 1));
+  }
+
+  /// Returns the MemoryDeallocationPolicy for this group.
+  MemDeallocPolicy getMemDeallocPolicy() const {
+    return static_cast<MemDeallocPolicy>(Id >> BitsForProt);
+  }
+
+  friend bool operator==(const AllocGroup &LHS, const AllocGroup &RHS) {
+    return LHS.Id == RHS.Id;
+  }
+
+  friend bool operator!=(const AllocGroup &LHS, const AllocGroup &RHS) {
+    return !(LHS == RHS);
+  }
+
+  friend bool operator<(const AllocGroup &LHS, const AllocGroup &RHS) {
+    return LHS.Id < RHS.Id;
+  }
+
+private:
+  AllocGroup(underlying_type RawId) : Id(RawId) {}
+  underlying_type Id = 0;
+};
+
+/// A specialized small-map for AllocGroups.
+///
+/// Iteration order is guaranteed to match key ordering.
+template <typename T> class AllocGroupSmallMap {
+private:
+  using ElemT = std::pair<AllocGroup, T>;
+  using VectorTy = SmallVector<ElemT, 4>;
+
+  static bool compareKey(const ElemT &E, const AllocGroup &G) {
+    return E.first < G;
+  }
+
+public:
+  using iterator = typename VectorTy::iterator;
+
+  AllocGroupSmallMap() = default;
+  AllocGroupSmallMap(std::initializer_list<std::pair<AllocGroup, T>> Inits) {
+    Elems.reserve(Inits.size());
+    for (const auto &E : Inits)
+      Elems.push_back(E);
+    llvm::sort(Elems, [](const ElemT &LHS, const ElemT &RHS) {
+      return LHS.first < RHS.first;
+    });
+  }
+
+  iterator begin() { return Elems.begin(); }
+  iterator end() { return Elems.end(); }
+  iterator find(AllocGroup G) {
+    auto I = lower_bound(Elems, G, compareKey);
+    return (I->first == G) ? I : end();
+  }
+
+  bool empty() const { return Elems.empty(); }
+  size_t size() const { return Elems.size(); }
+
+  T &operator[](AllocGroup G) {
+    auto I = lower_bound(Elems, G, compareKey);
+    if (I == Elems.end() || I->first != G)
+      I = Elems.insert(I, std::make_pair(G, T()));
+    return I->second;
+  }
+
+private:
+  VectorTy Elems;
+};
+
+/// Print an AllocGroup.
+raw_ostream &operator<<(raw_ostream &OS, AllocGroup AG);
+
+} // end namespace jitlink
+
+template <> struct DenseMapInfo<jitlink::MemProt> {
+  static inline jitlink::MemProt getEmptyKey() {
+    return jitlink::MemProt(~uint8_t(0));
+  }
+  static inline jitlink::MemProt getTombstoneKey() {
+    return jitlink::MemProt(~uint8_t(0) - 1);
+  }
+  static unsigned getHashValue(const jitlink::MemProt &Val) {
+    using UT = std::underlying_type_t<jitlink::MemProt>;
+    return DenseMapInfo<UT>::getHashValue(static_cast<UT>(Val));
+  }
+  static bool isEqual(const jitlink::MemProt &LHS,
+                      const jitlink::MemProt &RHS) {
+    return LHS == RHS;
+  }
+};
+
+template <> struct DenseMapInfo<jitlink::AllocGroup> {
+  static inline jitlink::AllocGroup getEmptyKey() {
+    return jitlink::AllocGroup(~uint8_t(0));
+  }
+  static inline jitlink::AllocGroup getTombstoneKey() {
+    return jitlink::AllocGroup(~uint8_t(0) - 1);
+  }
+  static unsigned getHashValue(const jitlink::AllocGroup &Val) {
+    return DenseMapInfo<jitlink::AllocGroup::underlying_type>::getHashValue(
+        Val.Id);
+  }
+  static bool isEqual(const jitlink::AllocGroup &LHS,
+                      const jitlink::AllocGroup &RHS) {
+    return LHS == RHS;
+  }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_EXECUTIONENGINE_JITLINK_MEMORYFLAGS_H
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/EPCDebugObjectRegistrar.h b/llvm/include/llvm/ExecutionEngine/Orc/EPCDebugObjectRegistrar.h
index 05ecb14dc79ea3..940d0d28ae83ee 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/EPCDebugObjectRegistrar.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/EPCDebugObjectRegistrar.h
@@ -14,6 +14,7 @@
 #define LLVM_EXECUTIONENGINE_ORC_EPCDEBUGOBJECTREGISTRAR_H
 
 #include "llvm/ExecutionEngine/JITSymbol.h"
+#include "llvm/ExecutionEngine/Orc/Shared/ExecutorAddress.h"
 #include "llvm/ExecutionEngine/Orc/Shared/WrapperFunctionUtils.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Memory.h"
@@ -32,7 +33,7 @@ class ExecutionSession;
 /// Abstract interface for registering debug objects in the executor process.
 class DebugObjectRegistrar {
 public:
-  virtual Error registerDebugObject(sys::MemoryBlock) = 0;
+  virtual Error registerDebugObject(ExecutorAddrRange TargetMem) = 0;
   virtual ~DebugObjectRegistrar() {}
 };
 
@@ -43,7 +44,7 @@ class EPCDebugObjectRegistrar : public DebugObjectRegistrar {
   EPCDebugObjectRegistrar(ExecutionSession &ES, ExecutorAddr RegisterFn)
       : ES(ES), RegisterFn(RegisterFn) {}
 
-  Error registerDebugObject(sys::MemoryBlock TargetMem) override;
+  Error registerDebugObject(ExecutorAddrRange TargetMem) override;
 
 private:
   ExecutionSession &ES;
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManager.h b/llvm/include/llvm/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManager.h
index 4de77a68dad880..b9825f17ec17c7 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManager.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManager.h
@@ -39,17 +39,58 @@ class EPCGenericJITLinkMemoryManager : public jitlink::JITLinkMemoryManager {
   EPCGenericJITLinkMemoryManager(ExecutorProcessControl &EPC, SymbolAddrs SAs)
       : EPC(EPC), SAs(SAs) {}
 
-  Expected<std::unique_ptr<Allocation>>
-  allocate(const jitlink::JITLinkDylib *JD,
-           const SegmentsRequestMap &Request) override;
+  void allocate(const jitlink::JITLinkDylib *JD, jitlink::LinkGraph &G,
+                OnAllocatedFunction OnAllocated) override;
+
+  // Use overloads from base class.
+  using JITLinkMemoryManager::allocate;
+
+  void deallocate(std::vector<FinalizedAlloc> Allocs,
+                  OnDeallocatedFunction OnDeallocated) override;
+
+  // Use overloads from base class.
+  using JITLinkMemoryManager::deallocate;
 
 private:
-  class Alloc;
+  class InFlightAlloc;
+
+  void completeAllocation(ExecutorAddr AllocAddr, jitlink::BasicLayout BL,
+                          OnAllocatedFunction OnAllocated);
 
   ExecutorProcessControl &EPC;
   SymbolAddrs SAs;
 };
 
+namespace shared {
+
+/// FIXME: This specialization should be moved into TargetProcessControlTypes.h
+///        (or whereever those types get merged to) once ORC depends on JITLink.
+template <>
+class SPSSerializationTraits<SPSExecutorAddr,
+                             jitlink::JITLinkMemoryManager::FinalizedAlloc> {
+public:
+  static size_t size(const jitlink::JITLinkMemoryManager::FinalizedAlloc &FA) {
+    return SPSArgList<SPSExecutorAddr>::size(ExecutorAddr(FA.getAddress()));
+  }
+
+  static bool
+  serialize(SPSOutputBuffer &OB,
+            const jitlink::JITLinkMemoryManager::FinalizedAlloc &FA) {
+    return SPSArgList<SPSExecutorAddr>::serialize(
+        OB, ExecutorAddr(FA.getAddress()));
+  }
+
+  static bool deserialize(SPSInputBuffer &IB,
+                          jitlink::JITLinkMemoryManager::FinalizedAlloc &FA) {
+    ExecutorAddr A;
+    if (!SPSArgList<SPSExecutorAddr>::deserialize(IB, A))
+      return false;
+    FA = jitlink::JITLinkMemoryManager::FinalizedAlloc(A.getValue());
+    return true;
+  }
+};
+
+} // end namespace shared
 } // end namespace orc
 } // end namespace llvm
 
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/EPCIndirectionUtils.h b/llvm/include/llvm/ExecutionEngine/Orc/EPCIndirectionUtils.h
index 64f16d507c97e2..92de5882bafe45 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/EPCIndirectionUtils.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/EPCIndirectionUtils.h
@@ -126,7 +126,7 @@ class EPCIndirectionUtils {
   }
 
 private:
-  using Allocation = jitlink::JITLinkMemoryManager::Allocation;
+  using FinalizedAlloc = jitlink::JITLinkMemoryManager::FinalizedAlloc;
 
   struct IndirectStubInfo {
     IndirectStubInfo() = default;
@@ -149,12 +149,12 @@ class EPCIndirectionUtils {
   ExecutorProcessControl &EPC;
   std::unique_ptr<ABISupport> ABI;
   JITTargetAddress ResolverBlockAddr;
-  std::unique_ptr<jitlink::JITLinkMemoryManager::Allocation> ResolverBlock;
+  FinalizedAlloc ResolverBlock;
   std::unique_ptr<TrampolinePool> TP;
   std::unique_ptr<LazyCallThroughManager> LCTM;
 
   std::vector<IndirectStubInfo> AvailableIndirectStubs;
-  std::vector<std::unique_ptr<Allocation>> IndirectStubAllocs;
+  std::vector<FinalizedAlloc> IndirectStubAllocs;
 };
 
 /// This will call writeResolver on the given EPCIndirectionUtils instance
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h b/llvm/include/llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h
index 5632118eee4e44..109922a46e26ad 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h
@@ -184,13 +184,13 @@ class ObjectLinkingLayer : public RTTIExtends<ObjectLinkingLayer, ObjectLayer>,
   }
 
 private:
-  using AllocPtr = std::unique_ptr<jitlink::JITLinkMemoryManager::Allocation>;
+  using FinalizedAlloc = jitlink::JITLinkMemoryManager::FinalizedAlloc;
 
   void modifyPassConfig(MaterializationResponsibility &MR,
                         jitlink::LinkGraph &G,
                         jitlink::PassConfiguration &PassConfig);
   void notifyLoaded(MaterializationResponsibility &MR);
-  Error notifyEmitted(MaterializationResponsibility &MR, AllocPtr Alloc);
+  Error notifyEmitted(MaterializationResponsibility &MR, FinalizedAlloc FA);
 
   Error handleRemoveResources(ResourceKey K) override;
   void handleTransferResources(ResourceKey DstKey, ResourceKey SrcKey) override;
@@ -201,7 +201,7 @@ class ObjectLinkingLayer : public RTTIExtends<ObjectLinkingLayer, ObjectLayer>,
   bool OverrideObjectFlags = false;
   bool AutoClaimObjectSymbols = false;
   ReturnObjectBufferFunction ReturnObjectBuffer;
-  DenseMap<ResourceKey, std::vector<AllocPtr>> Allocs;
+  DenseMap<ResourceKey, std::vector<FinalizedAlloc>> Allocs;
   std::vector<std::unique_ptr<Plugin>> Plugins;
 };
 
diff --git a/llvm/include/llvm/Support/Memory.h b/llvm/include/llvm/Support/Memory.h
index 31e0abbcdb61c9..a40ca9f813e00a 100644
--- a/llvm/include/llvm/Support/Memory.h
+++ b/llvm/include/llvm/Support/Memory.h
@@ -37,7 +37,7 @@ namespace sys {
     /// The size as it was allocated. This is always greater or equal to the
     /// size that was originally requested.
     size_t allocatedSize() const { return AllocatedSize; }
-  
+
   private:
     void *Address;    ///< Address of first byte of memory area
     size_t AllocatedSize; ///< Size, in bytes of the memory area
diff --git a/llvm/lib/ExecutionEngine/JITLink/CMakeLists.txt b/llvm/lib/ExecutionEngine/JITLink/CMakeLists.txt
index 4dfea9e6707a70..02157cb50d5888 100644
--- a/llvm/lib/ExecutionEngine/JITLink/CMakeLists.txt
+++ b/llvm/lib/ExecutionEngine/JITLink/CMakeLists.txt
@@ -3,6 +3,7 @@ add_llvm_component_library(LLVMJITLink
   JITLink.cpp
   JITLinkGeneric.cpp
   JITLinkMemoryManager.cpp
+  MemoryFlags.cpp
 
   # Formats:
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h b/llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h
index 05f84f35055492..fdc98775128620 100644
--- a/llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h
+++ b/llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h
@@ -36,11 +36,9 @@ class ELFLinkGraphBuilderBase {
   }
 
   Section &getCommonSection() {
-    if (!CommonSection) {
-      auto Prot = static_cast<sys::Memory::ProtectionFlags>(
-          sys::Memory::MF_READ | sys::Memory::MF_WRITE);
-      CommonSection = &G->createSection(CommonSectionName, Prot);
-    }
+    if (!CommonSection)
+      CommonSection =
+          &G->createSection(CommonSectionName, MemProt::Read | MemProt::Write);
     return *CommonSection;
   }
 
@@ -295,13 +293,11 @@ template <typename ELFT> Error ELFLinkGraphBuilder<ELFT>::graphifySections() {
     });
 
     // Get the section's memory protection flags.
-    sys::Memory::ProtectionFlags Prot;
+    MemProt Prot;
     if (Sec.sh_flags & ELF::SHF_EXECINSTR)
-      Prot = static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
-                                                       sys::Memory::MF_EXEC);
+      Prot = MemProt::Read | MemProt::Exec;
     else
-      Prot = static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
-                                                       sys::Memory::MF_WRITE);
+      Prot = MemProt::Read | MemProt::Write;
 
     // For now we just use this to skip the "undefined" section, probably need
     // to revist.
diff --git a/llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp b/llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp
index 1f8dbadd75e053..b057788ce3efc4 100644
--- a/llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp
@@ -80,16 +80,14 @@ class PerGraphGOTAndPLTStubsBuilder_ELF_riscv
 private:
   Section &getGOTSection() const {
     if (!GOTSection)
-      GOTSection = &G.createSection("$__GOT", sys::Memory::MF_READ);
+      GOTSection = &G.createSection("$__GOT", MemProt::Read);
     return *GOTSection;
   }
 
   Section &getStubsSection() const {
-    if (!StubsSection) {
-      auto StubsProt = static_cast<sys::Memory::ProtectionFlags>(
-          sys::Memory::MF_READ | sys::Memory::MF_EXEC);
-      StubsSection = &G.createSection("$__STUBS", StubsProt);
-    }
+    if (!StubsSection)
+      StubsSection =
+          &G.createSection("$__STUBS", MemProt::Read | MemProt::Exec);
     return *StubsSection;
   }
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp b/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
index 0a50f40ff9eb47..79c60493a901cb 100644
--- a/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
@@ -65,8 +65,7 @@ class PerGraphTLSInfoBuilder_ELF_x86_64
 
   Section &getTLSInfoSection() const {
     if (!TLSInfoSection)
-      TLSInfoSection =
-          &G.createSection(ELFTLSInfoSectionName, sys::Memory::MF_READ);
+      TLSInfoSection = &G.createSection(ELFTLSInfoSectionName, MemProt::Read);
     return *TLSInfoSection;
   }
 
@@ -172,16 +171,14 @@ class PerGraphGOTAndPLTStubsBuilder_ELF_x86_64
 private:
   Section &getGOTSection() const {
     if (!GOTSection)
-      GOTSection = &G.createSection(ELFGOTSectionName, sys::Memory::MF_READ);
+      GOTSection = &G.createSection(ELFGOTSectionName, MemProt::Read);
     return *GOTSection;
   }
 
   Section &getStubsSection() const {
-    if (!StubsSection) {
-      auto StubsProt = static_cast<sys::Memory::ProtectionFlags>(
-          sys::Memory::MF_READ | sys::Memory::MF_EXEC);
-      StubsSection = &G.createSection("$__STUBS", StubsProt);
-    }
+    if (!StubsSection)
+      StubsSection =
+          &G.createSection("$__STUBS", MemProt::Read | MemProt::Exec);
     return *StubsSection;
   }
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
index 8bb61a247b1cc4..706688aba4ec71 100644
--- a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
@@ -48,12 +48,21 @@ void JITLinkerBase::linkPhase1(std::unique_ptr<JITLinkerBase> Self) {
   if (auto Err = runPasses(Passes.PostPrunePasses))
     return Ctx->notifyFailed(std::move(Err));
 
-  // Sort blocks into segments.
-  auto Layout = layOutBlocks();
+  Ctx->getMemoryManager().allocate(
+      Ctx->getJITLinkDylib(), *G,
+      [S = std::move(Self)](AllocResult AR) mutable {
+        auto *TmpSelf = S.get();
+        TmpSelf->linkPhase2(std::move(S), std::move(AR));
+      });
+}
 
-  // Allocate memory for segments.
-  if (auto Err = allocateSegments(Layout))
-    return Ctx->notifyFailed(std::move(Err));
+void JITLinkerBase::linkPhase2(std::unique_ptr<JITLinkerBase> Self,
+                               AllocResult AR) {
+
+  if (AR)
+    Alloc = std::move(*AR);
+  else
+    return Ctx->notifyFailed(AR.takeError());
 
   LLVM_DEBUG({
     dbgs() << "Link graph \"" << G->getName()
@@ -73,16 +82,16 @@ void JITLinkerBase::linkPhase1(std::unique_ptr<JITLinkerBase> Self) {
 
   auto ExternalSymbols = getExternalSymbolNames();
 
-  // If there are no external symbols then proceed immediately with phase 2.
+  // If there are no external symbols then proceed immediately with phase 3.
   if (ExternalSymbols.empty()) {
     LLVM_DEBUG({
       dbgs() << "No external symbols for " << G->getName()
-             << ". Proceeding immediately with link phase 2.\n";
+             << ". Proceeding immediately with link phase 3.\n";
     });
     // FIXME: Once callee expressions are defined to be sequenced before
     //        argument expressions (c++17) we can simplify this. See below.
     auto &TmpSelf = *Self;
-    TmpSelf.linkPhase2(std::move(Self), AsyncLookupResult(), std::move(Layout));
+    TmpSelf.linkPhase3(std::move(Self), AsyncLookupResult());
     return;
   }
 
@@ -100,37 +109,31 @@ void JITLinkerBase::linkPhase1(std::unique_ptr<JITLinkerBase> Self) {
   //
   // Ctx->lookup(std::move(UnresolvedExternals),
   //             [Self=std::move(Self)](Expected<AsyncLookupResult> Result) {
-  //               Self->linkPhase2(std::move(Self), std::move(Result));
+  //               Self->linkPhase3(std::move(Self), std::move(Result));
   //             });
-  auto *TmpCtx = Ctx.get();
-  TmpCtx->lookup(std::move(ExternalSymbols),
-                 createLookupContinuation(
-                     [S = std::move(Self), L = std::move(Layout)](
-                         Expected<AsyncLookupResult> LookupResult) mutable {
-                       auto &TmpSelf = *S;
-                       TmpSelf.linkPhase2(std::move(S), std::move(LookupResult),
-                                          std::move(L));
-                     }));
+  Ctx->lookup(std::move(ExternalSymbols),
+              createLookupContinuation(
+                  [S = std::move(Self)](
+                      Expected<AsyncLookupResult> LookupResult) mutable {
+                    auto &TmpSelf = *S;
+                    TmpSelf.linkPhase3(std::move(S), std::move(LookupResult));
+                  }));
 }
 
-void JITLinkerBase::linkPhase2(std::unique_ptr<JITLinkerBase> Self,
-                               Expected<AsyncLookupResult> LR,
-                               SegmentLayoutMap Layout) {
+void JITLinkerBase::linkPhase3(std::unique_ptr<JITLinkerBase> Self,
+                               Expected<AsyncLookupResult> LR) {
 
   LLVM_DEBUG({
-    dbgs() << "Starting link phase 2 for graph " << G->getName() << "\n";
+    dbgs() << "Starting link phase 3 for graph " << G->getName() << "\n";
   });
 
   // If the lookup failed, bail out.
   if (!LR)
-    return deallocateAndBailOut(LR.takeError());
+    return abandonAllocAndBailOut(std::move(Self), LR.takeError());
 
   // Assign addresses to external addressables.
   applyLookupResult(*LR);
 
-  // Copy block content to working memory.
-  copyBlockContentToWorkingMemory(Layout, *Alloc);
-
   LLVM_DEBUG({
     dbgs() << "Link graph \"" << G->getName()
            << "\" before pre-fixup passes:\n";
@@ -138,7 +141,7 @@ void JITLinkerBase::linkPhase2(std::unique_ptr<JITLinkerBase> Self,
   });
 
   if (auto Err = runPasses(Passes.PreFixupPasses))
-    return deallocateAndBailOut(std::move(Err));
+    return abandonAllocAndBailOut(std::move(Self), std::move(Err));
 
   LLVM_DEBUG({
     dbgs() << "Link graph \"" << G->getName() << "\" before copy-and-fixup:\n";
@@ -147,7 +150,7 @@ void JITLinkerBase::linkPhase2(std::unique_ptr<JITLinkerBase> Self,
 
   // Fix up block content.
   if (auto Err = fixUpBlocks(*G))
-    return deallocateAndBailOut(std::move(Err));
+    return abandonAllocAndBailOut(std::move(Self), std::move(Err));
 
   LLVM_DEBUG({
     dbgs() << "Link graph \"" << G->getName() << "\" after copy-and-fixup:\n";
@@ -155,27 +158,25 @@ void JITLinkerBase::linkPhase2(std::unique_ptr<JITLinkerBase> Self,
   });
 
   if (auto Err = runPasses(Passes.PostFixupPasses))
-    return deallocateAndBailOut(std::move(Err));
-
-  // FIXME: Use move capture once we have c++14.
-  auto *UnownedSelf = Self.release();
-  auto Phase3Continuation = [UnownedSelf](Error Err) {
-    std::unique_ptr<JITLinkerBase> Self(UnownedSelf);
-    UnownedSelf->linkPhase3(std::move(Self), std::move(Err));
-  };
+    return abandonAllocAndBailOut(std::move(Self), std::move(Err));
 
-  Alloc->finalizeAsync(std::move(Phase3Continuation));
+  Alloc->finalize([S = std::move(Self)](FinalizeResult FR) mutable {
+    auto *TmpSelf = S.get();
+    TmpSelf->linkPhase4(std::move(S), std::move(FR));
+  });
 }
 
-void JITLinkerBase::linkPhase3(std::unique_ptr<JITLinkerBase> Self, Error Err) {
+void JITLinkerBase::linkPhase4(std::unique_ptr<JITLinkerBase> Self,
+                               FinalizeResult FR) {
 
   LLVM_DEBUG({
-    dbgs() << "Starting link phase 3 for graph " << G->getName() << "\n";
+    dbgs() << "Starting link phase 4 for graph " << G->getName() << "\n";
   });
 
-  if (Err)
-    return deallocateAndBailOut(std::move(Err));
-  Ctx->notifyFinalized(std::move(Alloc));
+  if (!FR)
+    return Ctx->notifyFailed(FR.takeError());
+
+  Ctx->notifyFinalized(std::move(*FR));
 
   LLVM_DEBUG({ dbgs() << "Link of graph " << G->getName() << " complete\n"; });
 }
@@ -187,131 +188,6 @@ Error JITLinkerBase::runPasses(LinkGraphPassList &Passes) {
   return Error::success();
 }
 
-JITLinkerBase::SegmentLayoutMap JITLinkerBase::layOutBlocks() {
-
-  SegmentLayoutMap Layout;
-
-  /// Partition blocks based on permissions and content vs. zero-fill.
-  for (auto *B : G->blocks()) {
-    auto &SegLists = Layout[B->getSection().getProtectionFlags()];
-    if (!B->isZeroFill())
-      SegLists.ContentBlocks.push_back(B);
-    else
-      SegLists.ZeroFillBlocks.push_back(B);
-  }
-
-  /// Sort blocks within each list.
-  for (auto &KV : Layout) {
-
-    auto CompareBlocks = [](const Block *LHS, const Block *RHS) {
-      // Sort by section, address and size
-      if (LHS->getSection().getOrdinal() != RHS->getSection().getOrdinal())
-        return LHS->getSection().getOrdinal() < RHS->getSection().getOrdinal();
-      if (LHS->getAddress() != RHS->getAddress())
-        return LHS->getAddress() < RHS->getAddress();
-      return LHS->getSize() < RHS->getSize();
-    };
-
-    auto &SegLists = KV.second;
-    llvm::sort(SegLists.ContentBlocks, CompareBlocks);
-    llvm::sort(SegLists.ZeroFillBlocks, CompareBlocks);
-  }
-
-  LLVM_DEBUG({
-    dbgs() << "Computed segment ordering:\n";
-    for (auto &KV : Layout) {
-      dbgs() << "  Segment "
-             << static_cast<sys::Memory::ProtectionFlags>(KV.first) << ":\n";
-      auto &SL = KV.second;
-      for (auto &SIEntry :
-           {std::make_pair(&SL.ContentBlocks, "content block"),
-            std::make_pair(&SL.ZeroFillBlocks, "zero-fill block")}) {
-        dbgs() << "    " << SIEntry.second << ":\n";
-        for (auto *B : *SIEntry.first)
-          dbgs() << "      " << *B << "\n";
-      }
-    }
-  });
-
-  return Layout;
-}
-
-Error JITLinkerBase::allocateSegments(const SegmentLayoutMap &Layout) {
-
-  // Compute segment sizes and allocate memory.
-  LLVM_DEBUG(dbgs() << "JIT linker requesting: { ");
-  JITLinkMemoryManager::SegmentsRequestMap Segments;
-  for (auto &KV : Layout) {
-    auto &Prot = KV.first;
-    auto &SegLists = KV.second;
-
-    uint64_t SegAlign = 1;
-
-    // Calculate segment content size.
-    size_t SegContentSize = 0;
-    for (auto *B : SegLists.ContentBlocks) {
-      SegAlign = std::max(SegAlign, B->getAlignment());
-      SegContentSize = alignToBlock(SegContentSize, *B);
-      SegContentSize += B->getSize();
-    }
-
-    uint64_t SegZeroFillStart = SegContentSize;
-    uint64_t SegZeroFillEnd = SegZeroFillStart;
-
-    for (auto *B : SegLists.ZeroFillBlocks) {
-      SegAlign = std::max(SegAlign, B->getAlignment());
-      SegZeroFillEnd = alignToBlock(SegZeroFillEnd, *B);
-      SegZeroFillEnd += B->getSize();
-    }
-
-    Segments[Prot] = {SegAlign, SegContentSize,
-                      SegZeroFillEnd - SegZeroFillStart};
-
-    LLVM_DEBUG({
-      dbgs() << (&KV == &*Layout.begin() ? "" : "; ")
-             << static_cast<sys::Memory::ProtectionFlags>(Prot)
-             << ": alignment = " << SegAlign
-             << ", content size = " << SegContentSize
-             << ", zero-fill size = " << (SegZeroFillEnd - SegZeroFillStart);
-    });
-  }
-  LLVM_DEBUG(dbgs() << " }\n");
-
-  if (auto AllocOrErr =
-          Ctx->getMemoryManager().allocate(Ctx->getJITLinkDylib(), Segments))
-    Alloc = std::move(*AllocOrErr);
-  else
-    return AllocOrErr.takeError();
-
-  LLVM_DEBUG({
-    dbgs() << "JIT linker got memory (working -> target):\n";
-    for (auto &KV : Layout) {
-      auto Prot = static_cast<sys::Memory::ProtectionFlags>(KV.first);
-      dbgs() << "  " << Prot << ": "
-             << (const void *)Alloc->getWorkingMemory(Prot).data() << " -> "
-             << formatv("{0:x16}", Alloc->getTargetMemory(Prot)) << "\n";
-    }
-  });
-
-  // Update block target addresses.
-  for (auto &KV : Layout) {
-    auto &Prot = KV.first;
-    auto &SL = KV.second;
-
-    JITTargetAddress NextBlockAddr =
-        Alloc->getTargetMemory(static_cast<sys::Memory::ProtectionFlags>(Prot));
-
-    for (auto *SIList : {&SL.ContentBlocks, &SL.ZeroFillBlocks})
-      for (auto *B : *SIList) {
-        NextBlockAddr = alignToBlock(NextBlockAddr, *B);
-        B->setAddress(NextBlockAddr);
-        NextBlockAddr += B->getSize();
-      }
-  }
-
-  return Error::success();
-}
-
 JITLinkContext::LookupMap JITLinkerBase::getExternalSymbolNames() const {
   // Identify unresolved external symbols.
   JITLinkContext::LookupMap UnresolvedExternals;
@@ -351,90 +227,13 @@ void JITLinkerBase::applyLookupResult(AsyncLookupResult Result) {
   });
 }
 
-void JITLinkerBase::copyBlockContentToWorkingMemory(
-    const SegmentLayoutMap &Layout, JITLinkMemoryManager::Allocation &Alloc) {
-
-  LLVM_DEBUG(dbgs() << "Copying block content:\n");
-  for (auto &KV : Layout) {
-    auto &Prot = KV.first;
-    auto &SegLayout = KV.second;
-
-    auto SegMem =
-        Alloc.getWorkingMemory(static_cast<sys::Memory::ProtectionFlags>(Prot));
-
-    LLVM_DEBUG({
-      dbgs() << "  Processing segment "
-             << static_cast<sys::Memory::ProtectionFlags>(Prot) << " [ "
-             << (const void *)SegMem.data() << " .. "
-             << (const void *)((char *)SegMem.data() + SegMem.size())
-             << " ]\n    Processing content sections:\n";
-    });
-
-    if (SegLayout.ContentBlocks.empty()) {
-      LLVM_DEBUG(dbgs() << "    No content blocks.\n");
-      continue;
-    }
-
-    size_t BlockOffset = 0;
-    size_t LastBlockEnd = 0;
-
-    for (auto *B : SegLayout.ContentBlocks) {
-      LLVM_DEBUG(dbgs() << "    " << *B << ":\n");
-
-      // Pad to alignment/alignment-offset.
-      BlockOffset = alignToBlock(BlockOffset, *B);
-
-      LLVM_DEBUG({
-        dbgs() << "      Bumped block offset to "
-               << formatv("{0:x}", BlockOffset) << " to meet block alignment "
-               << B->getAlignment() << " and alignment offset "
-               << B->getAlignmentOffset() << "\n";
-      });
-
-      // Zero pad up to alignment.
-      LLVM_DEBUG({
-        if (LastBlockEnd != BlockOffset)
-          dbgs() << "      Zero padding from " << formatv("{0:x}", LastBlockEnd)
-                 << " to " << formatv("{0:x}", BlockOffset) << "\n";
-      });
-
-      for (; LastBlockEnd != BlockOffset; ++LastBlockEnd)
-        *(SegMem.data() + LastBlockEnd) = 0;
-
-      // Copy initial block content.
-      LLVM_DEBUG({
-        dbgs() << "      Copying block " << *B << " content, "
-               << B->getContent().size() << " bytes, from "
-               << (const void *)B->getContent().data() << " to offset "
-               << formatv("{0:x}", BlockOffset) << "\n";
-      });
-      memcpy(SegMem.data() + BlockOffset, B->getContent().data(),
-             B->getContent().size());
-
-      // Point the block's content to the fixed up buffer.
-      B->setMutableContent(
-          {SegMem.data() + BlockOffset, B->getContent().size()});
-
-      // Update block end pointer.
-      LastBlockEnd = BlockOffset + B->getContent().size();
-      BlockOffset = LastBlockEnd;
-    }
-
-    // Zero pad the rest of the segment.
-    LLVM_DEBUG({
-      dbgs() << "    Zero padding end of segment from offset "
-             << formatv("{0:x}", LastBlockEnd) << " to "
-             << formatv("{0:x}", SegMem.size()) << "\n";
-    });
-    for (; LastBlockEnd != SegMem.size(); ++LastBlockEnd)
-      *(SegMem.data() + LastBlockEnd) = 0;
-  }
-}
-
-void JITLinkerBase::deallocateAndBailOut(Error Err) {
+void JITLinkerBase::abandonAllocAndBailOut(std::unique_ptr<JITLinkerBase> Self,
+                                           Error Err) {
   assert(Err && "Should not be bailing out on success value");
-  assert(Alloc && "can not call deallocateAndBailOut before allocation");
-  Ctx->notifyFailed(joinErrors(std::move(Err), Alloc->deallocate()));
+  assert(Alloc && "can not call abandonAllocAndBailOut before allocation");
+  Alloc->abandon([S = std::move(Self), E1 = std::move(Err)](Error E2) mutable {
+    S->Ctx->notifyFailed(joinErrors(std::move(E1), std::move(E2)));
+  });
 }
 
 void prune(LinkGraph &G) {
diff --git a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h
index 6b815fe4fb31ec..e4fdda0783a4ed 100644
--- a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h
+++ b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h
@@ -42,14 +42,9 @@ class JITLinkerBase {
   virtual ~JITLinkerBase();
 
 protected:
-  struct SegmentLayout {
-    using BlocksList = std::vector<Block *>;
-
-    BlocksList ContentBlocks;
-    BlocksList ZeroFillBlocks;
-  };
-
-  using SegmentLayoutMap = DenseMap<unsigned, SegmentLayout>;
+  using InFlightAlloc = JITLinkMemoryManager::InFlightAlloc;
+  using AllocResult = Expected<std::unique_ptr<InFlightAlloc>>;
+  using FinalizeResult = Expected<JITLinkMemoryManager::FinalizedAlloc>;
 
   // Returns the PassConfiguration for this instance. This can be used by
   // JITLinkerBase implementations to add late passes that reference their
@@ -61,39 +56,27 @@ class JITLinkerBase {
   //   1.1: Run pre-prune passes
   //   1.2: Prune graph
   //   1.3: Run post-prune passes
-  //   1.4: Sort blocks into segments
-  //   1.5: Allocate segment memory, update node vmaddrs to target vmaddrs
-  //   1.6: Run post-allocation passes
-  //   1.7: Notify context of final assigned symbol addresses
-  //   1.8: Identify external symbols and make an async call to resolve
+  //   1.4: Allocate memory.
   void linkPhase1(std::unique_ptr<JITLinkerBase> Self);
 
   // Phase 2:
-  //   2.1: Apply resolution results
-  //   2.2: Run pre-fixup passes
-  //   2.3: Fix up block contents
-  //   2.4: Run post-fixup passes
-  //   2.5: Make an async call to transfer and finalize memory.
-  void linkPhase2(std::unique_ptr<JITLinkerBase> Self,
-                  Expected<AsyncLookupResult> LookupResult,
-                  SegmentLayoutMap Layout);
+  //   2.2: Run post-allocation passes
+  //   2.3: Notify context of final assigned symbol addresses
+  //   2.4: Identify external symbols and make an async call to resolve
+  void linkPhase2(std::unique_ptr<JITLinkerBase> Self, AllocResult AR);
 
   // Phase 3:
-  //   3.1: Call OnFinalized callback, handing off allocation.
-  void linkPhase3(std::unique_ptr<JITLinkerBase> Self, Error Err);
-
-  // Align a JITTargetAddress to conform with block alignment requirements.
-  static JITTargetAddress alignToBlock(JITTargetAddress Addr, Block &B) {
-    uint64_t Delta = (B.getAlignmentOffset() - Addr) % B.getAlignment();
-    return Addr + Delta;
-  }
-
-  // Align a pointer to conform with block alignment requirements.
-  static char *alignToBlock(char *P, Block &B) {
-    uint64_t PAddr = static_cast<uint64_t>(reinterpret_cast<uintptr_t>(P));
-    uint64_t Delta = (B.getAlignmentOffset() - PAddr) % B.getAlignment();
-    return P + Delta;
-  }
+  //   3.1: Apply resolution results
+  //   3.2: Run pre-fixup passes
+  //   3.3: Fix up block contents
+  //   3.4: Run post-fixup passes
+  //   3.5: Make an async call to transfer and finalize memory.
+  void linkPhase3(std::unique_ptr<JITLinkerBase> Self,
+                  Expected<AsyncLookupResult> LookupResult);
+
+  // Phase 4:
+  //   4.1: Call OnFinalized callback, handing off allocation.
+  void linkPhase4(std::unique_ptr<JITLinkerBase> Self, FinalizeResult FR);
 
 private:
   // Run all passes in the given pass list, bailing out immediately if any pass
@@ -104,18 +87,14 @@ class JITLinkerBase {
   // Implemented in JITLinker.
   virtual Error fixUpBlocks(LinkGraph &G) const = 0;
 
-  SegmentLayoutMap layOutBlocks();
-  Error allocateSegments(const SegmentLayoutMap &Layout);
   JITLinkContext::LookupMap getExternalSymbolNames() const;
   void applyLookupResult(AsyncLookupResult LR);
-  void copyBlockContentToWorkingMemory(const SegmentLayoutMap &Layout,
-                                       JITLinkMemoryManager::Allocation &Alloc);
-  void deallocateAndBailOut(Error Err);
+  void abandonAllocAndBailOut(std::unique_ptr<JITLinkerBase> Self, Error Err);
 
   std::unique_ptr<JITLinkContext> Ctx;
   std::unique_ptr<LinkGraph> G;
   PassConfiguration Passes;
-  std::unique_ptr<JITLinkMemoryManager::Allocation> Alloc;
+  std::unique_ptr<InFlightAlloc> Alloc;
 };
 
 template <typename LinkerImpl> class JITLinker : public JITLinkerBase {
@@ -152,6 +131,8 @@ template <typename LinkerImpl> class JITLinker : public JITLinkerBase {
 
       // Copy Block data and apply fixups.
       LLVM_DEBUG(dbgs() << "    Applying fixups.\n");
+      assert((!B->isZeroFill() || B->edges_size() == 0) &&
+             "Edges in zero-fill block?");
       for (auto &E : B->edges()) {
 
         // Skip non-relocation edges.
diff --git a/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp b/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp
index d572a0b822559e..ff3d71fc383afb 100644
--- a/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp
@@ -7,128 +7,489 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h"
+#include "llvm/ExecutionEngine/JITLink/JITLink.h"
+#include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/Process.h"
 
+#define DEBUG_TYPE "jitlink"
+
 namespace llvm {
 namespace jitlink {
 
 JITLinkMemoryManager::~JITLinkMemoryManager() = default;
-JITLinkMemoryManager::Allocation::~Allocation() = default;
-
-Expected<std::unique_ptr<JITLinkMemoryManager::Allocation>>
-InProcessMemoryManager::allocate(const JITLinkDylib *JD,
-                                 const SegmentsRequestMap &Request) {
-
-  using AllocationMap = DenseMap<unsigned, sys::MemoryBlock>;
-
-  // Local class for allocation.
-  class IPMMAlloc : public Allocation {
-  public:
-    IPMMAlloc(AllocationMap SegBlocks) : SegBlocks(std::move(SegBlocks)) {}
-    MutableArrayRef<char> getWorkingMemory(ProtectionFlags Seg) override {
-      assert(SegBlocks.count(Seg) && "No allocation for segment");
-      return {static_cast<char *>(SegBlocks[Seg].base()),
-              SegBlocks[Seg].allocatedSize()};
+JITLinkMemoryManager::InFlightAlloc::~InFlightAlloc() = default;
+
+static Error runAllocAction(JITLinkMemoryManager::AllocActionCall &C) {
+  using DeallocFnTy = char *(*)(const void *, size_t);
+  auto *Fn = jitTargetAddressToPointer<DeallocFnTy>(C.FnAddr);
+
+  if (char *ErrMsg = Fn(jitTargetAddressToPointer<const void *>(C.CtxAddr),
+                        static_cast<size_t>(C.CtxSize))) {
+    auto E = make_error<StringError>(ErrMsg, inconvertibleErrorCode());
+    free(ErrMsg);
+    return E;
+  }
+
+  return Error::success();
+}
+
+// Align a JITTargetAddress to conform with block alignment requirements.
+static JITTargetAddress alignToBlock(JITTargetAddress Addr, Block &B) {
+  uint64_t Delta = (B.getAlignmentOffset() - Addr) % B.getAlignment();
+  return Addr + Delta;
+}
+
+BasicLayout::BasicLayout(LinkGraph &G) : G(G) {
+
+  for (auto &Sec : G.sections()) {
+    // Skip empty sections.
+    if (empty(Sec.blocks()))
+      continue;
+
+    auto &Seg = Segments[{Sec.getMemProt(), Sec.getMemDeallocPolicy()}];
+    for (auto *B : Sec.blocks())
+      if (LLVM_LIKELY(!B->isZeroFill()))
+        Seg.ContentBlocks.push_back(B);
+      else
+        Seg.ZeroFillBlocks.push_back(B);
+  }
+
+  // Build Segments map.
+  auto CompareBlocks = [](const Block *LHS, const Block *RHS) {
+    // Sort by section, address and size
+    if (LHS->getSection().getOrdinal() != RHS->getSection().getOrdinal())
+      return LHS->getSection().getOrdinal() < RHS->getSection().getOrdinal();
+    if (LHS->getAddress() != RHS->getAddress())
+      return LHS->getAddress() < RHS->getAddress();
+    return LHS->getSize() < RHS->getSize();
+  };
+
+  LLVM_DEBUG(dbgs() << "Generated BasicLayout for " << G.getName() << ":\n");
+  for (auto &KV : Segments) {
+    auto &Seg = KV.second;
+
+    llvm::sort(Seg.ContentBlocks, CompareBlocks);
+    llvm::sort(Seg.ZeroFillBlocks, CompareBlocks);
+
+    for (auto *B : Seg.ContentBlocks) {
+      Seg.ContentSize = alignToBlock(Seg.ContentSize, *B);
+      Seg.ContentSize += B->getSize();
+      Seg.Alignment = std::max(Seg.Alignment, Align(B->getAlignment()));
+    }
+
+    uint64_t SegEndOffset = Seg.ContentSize;
+    for (auto *B : Seg.ZeroFillBlocks) {
+      SegEndOffset = alignToBlock(SegEndOffset, *B);
+      SegEndOffset += B->getSize();
+      Seg.Alignment = std::max(Seg.Alignment, Align(B->getAlignment()));
+    }
+    Seg.ZeroFillSize = SegEndOffset - Seg.ContentSize;
+
+    LLVM_DEBUG({
+      dbgs() << "  Seg " << KV.first
+             << ": content-size=" << formatv("{0:x}", Seg.ContentSize)
+             << ", zero-fill-size=" << formatv("{0:x}", Seg.ZeroFillSize)
+             << ", align=" << formatv("{0:x}", Seg.Alignment.value()) << "\n";
+    });
+  }
+}
+
+Expected<BasicLayout::ContiguousPageBasedLayoutSizes>
+BasicLayout::getContiguousPageBasedLayoutSizes(uint64_t PageSize) {
+  ContiguousPageBasedLayoutSizes SegsSizes;
+
+  for (auto &KV : segments()) {
+    auto &AG = KV.first;
+    auto &Seg = KV.second;
+
+    if (Seg.Alignment > PageSize)
+      return make_error<StringError>("Segment alignment greater than page size",
+                                     inconvertibleErrorCode());
+
+    uint64_t SegSize = alignTo(Seg.ContentSize + Seg.ZeroFillSize, PageSize);
+    if (AG.getMemDeallocPolicy() == MemDeallocPolicy::Standard)
+      SegsSizes.StandardSegs += SegSize;
+    else
+      SegsSizes.FinalizeSegs += SegSize;
+  }
+
+  return SegsSizes;
+}
+
+Error BasicLayout::apply() {
+  for (auto &KV : Segments) {
+    auto &Seg = KV.second;
+
+    assert(!(Seg.ContentBlocks.empty() && Seg.ZeroFillBlocks.empty()) &&
+           "Empty section recorded?");
+
+    for (auto *B : Seg.ContentBlocks) {
+      // Align addr and working-mem-offset.
+      Seg.Addr = alignToBlock(Seg.Addr, *B);
+      Seg.NextWorkingMemOffset = alignToBlock(Seg.NextWorkingMemOffset, *B);
+
+      // Update block addr.
+      B->setAddress(Seg.Addr);
+      Seg.Addr += B->getSize();
+
+      // Copy content to working memory, then update content to point at working
+      // memory.
+      memcpy(Seg.WorkingMem + Seg.NextWorkingMemOffset, B->getContent().data(),
+             B->getSize());
+      B->setMutableContent(
+          {Seg.WorkingMem + Seg.NextWorkingMemOffset, B->getSize()});
+      Seg.NextWorkingMemOffset += B->getSize();
+    }
+
+    for (auto *B : Seg.ZeroFillBlocks) {
+      // Align addr.
+      Seg.Addr = alignToBlock(Seg.Addr, *B);
+      // Update block addr.
+      B->setAddress(Seg.Addr);
+      Seg.Addr += B->getSize();
+    }
+
+    Seg.ContentBlocks.clear();
+    Seg.ZeroFillBlocks.clear();
+  }
+
+  return Error::success();
+}
+
+JITLinkMemoryManager::AllocActions &BasicLayout::graphAllocActions() {
+  return G.allocActions();
+}
+
+void SimpleSegmentAlloc::Create(JITLinkMemoryManager &MemMgr,
+                                const JITLinkDylib *JD, SegmentMap Segments,
+                                OnCreatedFunction OnCreated) {
+
+  static_assert(AllocGroup::NumGroups == 16,
+                "AllocGroup has changed. Section names below must be updated");
+  StringRef AGSectionNames[] = {
+      "__---.standard", "__R--.standard", "__-W-.standard", "__RW-.standard",
+      "__--X.standard", "__R-X.standard", "__-WX.standard", "__RWX.standard",
+      "__---.finalize", "__R--.finalize", "__-W-.finalize", "__RW-.finalize",
+      "__--X.finalize", "__R-X.finalize", "__-WX.finalize", "__RWX.finalize"};
+
+  auto G =
+      std::make_unique<LinkGraph>("", Triple(), 0, support::native, nullptr);
+  AllocGroupSmallMap<Block *> ContentBlocks;
+
+  JITTargetAddress NextAddr = 0x100000;
+  for (auto &KV : Segments) {
+    auto &AG = KV.first;
+    auto &Seg = KV.second;
+
+    auto AGSectionName =
+        AGSectionNames[static_cast<unsigned>(AG.getMemProt()) |
+                       static_cast<bool>(AG.getMemDeallocPolicy()) << 3];
+
+    auto &Sec = G->createSection(AGSectionName, AG.getMemProt());
+    Sec.setMemDeallocPolicy(AG.getMemDeallocPolicy());
+
+    if (Seg.ContentSize != 0) {
+      NextAddr = alignTo(NextAddr, Seg.ContentAlign);
+      auto &B =
+          G->createMutableContentBlock(Sec, G->allocateBuffer(Seg.ContentSize),
+                                       NextAddr, Seg.ContentAlign.value(), 0);
+      ContentBlocks[AG] = &B;
+      NextAddr += Seg.ContentSize;
+    }
+  }
+
+  // GRef declared separately since order-of-argument-eval isn't specified.
+  auto &GRef = *G;
+  MemMgr.allocate(JD, GRef,
+                  [G = std::move(G), ContentBlocks = std::move(ContentBlocks),
+                   OnCreated = std::move(OnCreated)](
+                      JITLinkMemoryManager::AllocResult Alloc) mutable {
+                    if (!Alloc)
+                      OnCreated(Alloc.takeError());
+                    else
+                      OnCreated(SimpleSegmentAlloc(std::move(G),
+                                                   std::move(ContentBlocks),
+                                                   std::move(*Alloc)));
+                  });
+}
+
+Expected<SimpleSegmentAlloc>
+SimpleSegmentAlloc::Create(JITLinkMemoryManager &MemMgr, const JITLinkDylib *JD,
+                           SegmentMap Segments) {
+  std::promise<MSVCPExpected<SimpleSegmentAlloc>> AllocP;
+  auto AllocF = AllocP.get_future();
+  Create(MemMgr, JD, std::move(Segments),
+         [&](Expected<SimpleSegmentAlloc> Result) {
+           AllocP.set_value(std::move(Result));
+         });
+  return AllocF.get();
+}
+
+SimpleSegmentAlloc::SimpleSegmentAlloc(SimpleSegmentAlloc &&) = default;
+SimpleSegmentAlloc &
+SimpleSegmentAlloc::operator=(SimpleSegmentAlloc &&) = default;
+SimpleSegmentAlloc::~SimpleSegmentAlloc() {}
+
+SimpleSegmentAlloc::SegmentInfo SimpleSegmentAlloc::getSegInfo(AllocGroup AG) {
+  auto I = ContentBlocks.find(AG);
+  if (I != ContentBlocks.end()) {
+    auto &B = *I->second;
+    return {B.getAddress(), B.getAlreadyMutableContent()};
+  }
+  return {};
+}
+
+SimpleSegmentAlloc::SimpleSegmentAlloc(
+    std::unique_ptr<LinkGraph> G, AllocGroupSmallMap<Block *> ContentBlocks,
+    std::unique_ptr<JITLinkMemoryManager::InFlightAlloc> Alloc)
+    : G(std::move(G)), ContentBlocks(std::move(ContentBlocks)),
+      Alloc(std::move(Alloc)) {}
+
+class InProcessMemoryManager::IPInFlightAlloc
+    : public JITLinkMemoryManager::InFlightAlloc {
+public:
+  IPInFlightAlloc(InProcessMemoryManager &MemMgr, LinkGraph &G, BasicLayout BL,
+                  sys::MemoryBlock StandardSegments,
+                  sys::MemoryBlock FinalizationSegments)
+      : MemMgr(MemMgr), G(G), BL(std::move(BL)),
+        StandardSegments(std::move(StandardSegments)),
+        FinalizationSegments(std::move(FinalizationSegments)) {}
+
+  void finalize(OnFinalizedFunction OnFinalized) override {
+
+    // Apply memory protections to all segments.
+    if (auto Err = applyProtections()) {
+      OnFinalized(std::move(Err));
+      return;
     }
-    JITTargetAddress getTargetMemory(ProtectionFlags Seg) override {
-      assert(SegBlocks.count(Seg) && "No allocation for segment");
-      return pointerToJITTargetAddress(SegBlocks[Seg].base());
+
+    // Run finalization actions.
+    // FIXME: Roll back previous successful actions on failure.
+    std::vector<AllocActionCall> DeallocActions;
+    DeallocActions.reserve(G.allocActions().size());
+    for (auto &ActPair : G.allocActions()) {
+      if (ActPair.Finalize.FnAddr)
+        if (auto Err = runAllocAction(ActPair.Finalize)) {
+          OnFinalized(std::move(Err));
+          return;
+        }
+      if (ActPair.Dealloc.FnAddr)
+        DeallocActions.push_back(ActPair.Dealloc);
     }
-    void finalizeAsync(FinalizeContinuation OnFinalize) override {
-      OnFinalize(applyProtections());
+    G.allocActions().clear();
+
+    // Release the finalize segments slab.
+    if (auto EC = sys::Memory::releaseMappedMemory(FinalizationSegments)) {
+      OnFinalized(errorCodeToError(EC));
+      return;
     }
-    Error deallocate() override {
-      if (SegBlocks.empty())
-        return Error::success();
-      void *SlabStart = SegBlocks.begin()->second.base();
-      char *SlabEnd = (char *)SlabStart;
-      for (auto &KV : SegBlocks) {
-        SlabStart = std::min(SlabStart, KV.second.base());
-        SlabEnd = std::max(SlabEnd, (char *)(KV.second.base()) +
-                                        KV.second.allocatedSize());
-      }
-      size_t SlabSize = SlabEnd - (char *)SlabStart;
-      assert((SlabSize % sys::Process::getPageSizeEstimate()) == 0 &&
-             "Slab size is not a multiple of page size");
-      sys::MemoryBlock Slab(SlabStart, SlabSize);
-      if (auto EC = sys::Memory::releaseMappedMemory(Slab))
+
+    // Continue with finalized allocation.
+    OnFinalized(MemMgr.createFinalizedAlloc(std::move(StandardSegments),
+                                            std::move(DeallocActions)));
+  }
+
+  void abandon(OnAbandonedFunction OnAbandoned) override {
+    Error Err = Error::success();
+    if (auto EC = sys::Memory::releaseMappedMemory(FinalizationSegments))
+      Err = joinErrors(std::move(Err), errorCodeToError(EC));
+    if (auto EC = sys::Memory::releaseMappedMemory(StandardSegments))
+      Err = joinErrors(std::move(Err), errorCodeToError(EC));
+    OnAbandoned(std::move(Err));
+  }
+
+private:
+  Error applyProtections() {
+    for (auto &KV : BL.segments()) {
+      const auto &AG = KV.first;
+      auto &Seg = KV.second;
+
+      auto Prot = toSysMemoryProtectionFlags(AG.getMemProt());
+
+      uint64_t SegSize =
+          alignTo(Seg.ContentSize + Seg.ZeroFillSize, MemMgr.PageSize);
+      sys::MemoryBlock MB(Seg.WorkingMem, SegSize);
+      if (auto EC = sys::Memory::protectMappedMemory(MB, Prot))
         return errorCodeToError(EC);
-      return Error::success();
+      if (Prot & sys::Memory::MF_EXEC)
+        sys::Memory::InvalidateInstructionCache(MB.base(), MB.allocatedSize());
     }
+    return Error::success();
+  }
+
+  InProcessMemoryManager &MemMgr;
+  LinkGraph &G;
+  BasicLayout BL;
+  sys::MemoryBlock StandardSegments;
+  sys::MemoryBlock FinalizationSegments;
+};
 
-  private:
-    Error applyProtections() {
-      for (auto &KV : SegBlocks) {
-        auto &Prot = KV.first;
-        auto &Block = KV.second;
-        if (auto EC = sys::Memory::protectMappedMemory(Block, Prot))
-          return errorCodeToError(EC);
-        if (Prot & sys::Memory::MF_EXEC)
-          sys::Memory::InvalidateInstructionCache(Block.base(),
-                                                  Block.allocatedSize());
-      }
-      return Error::success();
+Expected<std::unique_ptr<InProcessMemoryManager>>
+InProcessMemoryManager::Create() {
+  if (auto PageSize = sys::Process::getPageSize())
+    return std::make_unique<InProcessMemoryManager>(*PageSize);
+  else
+    return PageSize.takeError();
+}
+
+void InProcessMemoryManager::allocate(const JITLinkDylib *JD, LinkGraph &G,
+                                      OnAllocatedFunction OnAllocated) {
+
+  // FIXME: Just check this once on startup.
+  if (!isPowerOf2_64((uint64_t)PageSize)) {
+    OnAllocated(make_error<StringError>("Page size is not a power of 2",
+                                        inconvertibleErrorCode()));
+    return;
+  }
+
+  BasicLayout BL(G);
+
+  /// Scan the request and calculate the group and total sizes.
+  /// Check that segment size is no larger than a page.
+  auto SegsSizes = BL.getContiguousPageBasedLayoutSizes(PageSize);
+  if (!SegsSizes) {
+    OnAllocated(SegsSizes.takeError());
+    return;
+  }
+
+  /// Check that the total size requested (including zero fill) is not larger
+  /// than a size_t.
+  if (SegsSizes->total() > std::numeric_limits<size_t>::max()) {
+    OnAllocated(make_error<JITLinkError>(
+        "Total requested size " + formatv("{0:x}", SegSizes->total()) +
+        " for graph " + G.getName() + " exceeds address space"));
+    return;
+  }
+
+  // Allocate one slab for the whole thing (to make sure everything is
+  // in-range), then partition into standard and finalization blocks.
+  //
+  // FIXME: Make two separate allocations in the future to reduce
+  // fragmentation: finalization segments will usually be a single page, and
+  // standard segments are likely to be more than one page. Where multiple
+  // allocations are in-flight at once (likely) the current approach will leave
+  // a lot of single-page holes.
+  sys::MemoryBlock Slab;
+  sys::MemoryBlock StandardSegsMem;
+  sys::MemoryBlock FinalizeSegsMem;
+  {
+    const sys::Memory::ProtectionFlags ReadWrite =
+        static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
+                                                  sys::Memory::MF_WRITE);
+
+    std::error_code EC;
+    Slab = sys::Memory::allocateMappedMemory(SegsSizes->total(), nullptr,
+                                             ReadWrite, EC);
+
+    if (EC) {
+      OnAllocated(errorCodeToError(EC));
+      return;
     }
 
-    AllocationMap SegBlocks;
-  };
+    // Zero-fill the whole slab up-front.
+    memset(Slab.base(), 0, Slab.allocatedSize());
 
-  if (!isPowerOf2_64((uint64_t)sys::Process::getPageSizeEstimate()))
-    return make_error<StringError>("Page size is not a power of 2",
-                                   inconvertibleErrorCode());
+    StandardSegsMem = {Slab.base(),
+                       static_cast<size_t>(SegsSizes->StandardSegs)};
+    FinalizeSegsMem = {(void *)((char *)Slab.base() + SegsSizes->StandardSegs),
+                       static_cast<size_t>(SegsSizes->FinalizeSegs)};
+  }
 
-  AllocationMap Blocks;
-  const sys::Memory::ProtectionFlags ReadWrite =
-      static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
-                                                sys::Memory::MF_WRITE);
+  auto NextStandardSegAddr = pointerToJITTargetAddress(StandardSegsMem.base());
+  auto NextFinalizeSegAddr = pointerToJITTargetAddress(FinalizeSegsMem.base());
 
-  // Compute the total number of pages to allocate.
-  size_t TotalSize = 0;
-  for (auto &KV : Request) {
-    const auto &Seg = KV.second;
+  LLVM_DEBUG({
+    dbgs() << "InProcessMemoryManager allocated:\n";
+    if (SegsSizes->StandardSegs)
+      dbgs() << formatv("  [ {0:x16} -- {1:x16} ]", NextStandardSegAddr,
+                        NextStandardSegAddr + StandardSegsMem.allocatedSize())
+             << " to stardard segs\n";
+    else
+      dbgs() << "  no standard segs\n";
+    if (SegsSizes->FinalizeSegs)
+      dbgs() << formatv("  [ {0:x16} -- {1:x16} ]", NextFinalizeSegAddr,
+                        NextFinalizeSegAddr + FinalizeSegsMem.allocatedSize())
+             << " to finalize segs\n";
+    else
+      dbgs() << "  no finalize segs\n";
+  });
 
-    if (Seg.getAlignment() > sys::Process::getPageSizeEstimate())
-      return make_error<StringError>("Cannot request higher than page "
-                                     "alignment",
-                                     inconvertibleErrorCode());
+  // Build ProtMap, assign addresses.
+  for (auto &KV : BL.segments()) {
+    auto &AG = KV.first;
+    auto &Seg = KV.second;
+
+    auto &SegAddr = (AG.getMemDeallocPolicy() == MemDeallocPolicy::Standard)
+                        ? NextStandardSegAddr
+                        : NextFinalizeSegAddr;
+
+    Seg.WorkingMem = jitTargetAddressToPointer<char *>(SegAddr);
+    Seg.Addr = SegAddr;
+
+    SegAddr += alignTo(Seg.ContentSize + Seg.ZeroFillSize, PageSize);
+  }
 
-    TotalSize = alignTo(TotalSize, sys::Process::getPageSizeEstimate());
-    TotalSize += Seg.getContentSize();
-    TotalSize += Seg.getZeroFillSize();
+  if (auto Err = BL.apply()) {
+    OnAllocated(std::move(Err));
+    return;
   }
 
-  // Allocate one slab to cover all the segments.
-  std::error_code EC;
-  auto SlabRemaining =
-      sys::Memory::allocateMappedMemory(TotalSize, nullptr, ReadWrite, EC);
+  OnAllocated(std::make_unique<IPInFlightAlloc>(*this, G, std::move(BL),
+                                                std::move(StandardSegsMem),
+                                                std::move(FinalizeSegsMem)));
+}
 
-  if (EC)
-    return errorCodeToError(EC);
+void InProcessMemoryManager::deallocate(std::vector<FinalizedAlloc> Allocs,
+                                        OnDeallocatedFunction OnDeallocated) {
+  std::vector<sys::MemoryBlock> StandardSegmentsList;
+  std::vector<std::vector<AllocActionCall>> DeallocActionsList;
 
-  // Allocate segment memory from the slab.
-  for (auto &KV : Request) {
+  {
+    std::lock_guard<std::mutex> Lock(FinalizedAllocsMutex);
+    for (auto &Alloc : Allocs) {
+      auto *FA =
+          jitTargetAddressToPointer<FinalizedAllocInfo *>(Alloc.release());
+      StandardSegmentsList.push_back(std::move(FA->StandardSegments));
+      if (!FA->DeallocActions.empty())
+        DeallocActionsList.push_back(std::move(FA->DeallocActions));
+      FA->~FinalizedAllocInfo();
+      FinalizedAllocInfos.Deallocate(FA);
+    }
+  }
 
-    const auto &Seg = KV.second;
+  Error DeallocErr = Error::success();
 
-    uint64_t SegmentSize = alignTo(Seg.getContentSize() + Seg.getZeroFillSize(),
-                                   sys::Process::getPageSizeEstimate());
-    assert(SlabRemaining.allocatedSize() >= SegmentSize &&
-           "Mapping exceeds allocation");
+  while (!DeallocActionsList.empty()) {
+    auto &DeallocActions = DeallocActionsList.back();
+    auto &StandardSegments = StandardSegmentsList.back();
 
-    sys::MemoryBlock SegMem(SlabRemaining.base(), SegmentSize);
-    SlabRemaining = sys::MemoryBlock((char *)SlabRemaining.base() + SegmentSize,
-                                     SlabRemaining.allocatedSize() - SegmentSize);
+    /// Run any deallocate calls.
+    while (!DeallocActions.empty()) {
+      if (auto Err = runAllocAction(DeallocActions.back()))
+        DeallocErr = joinErrors(std::move(DeallocErr), std::move(Err));
+      DeallocActions.pop_back();
+    }
 
-    // Zero out the zero-fill memory.
-    memset(static_cast<char *>(SegMem.base()) + Seg.getContentSize(), 0,
-           Seg.getZeroFillSize());
+    /// Release the standard segments slab.
+    if (auto EC = sys::Memory::releaseMappedMemory(StandardSegments))
+      DeallocErr = joinErrors(std::move(DeallocErr), errorCodeToError(EC));
 
-    // Record the block for this segment.
-    Blocks[KV.first] = std::move(SegMem);
+    DeallocActionsList.pop_back();
+    StandardSegmentsList.pop_back();
   }
 
-  return std::unique_ptr<InProcessMemoryManager::Allocation>(
-      new IPMMAlloc(std::move(Blocks)));
+  OnDeallocated(std::move(DeallocErr));
+}
+
+JITLinkMemoryManager::FinalizedAlloc
+InProcessMemoryManager::createFinalizedAlloc(
+    sys::MemoryBlock StandardSegments,
+    std::vector<AllocActionCall> DeallocActions) {
+  std::lock_guard<std::mutex> Lock(FinalizedAllocsMutex);
+  auto *FA = FinalizedAllocInfos.Allocate<FinalizedAllocInfo>();
+  new (FA) FinalizedAllocInfo(
+      {std::move(StandardSegments), std::move(DeallocActions)});
+  return FinalizedAlloc(pointerToJITTargetAddress(FA));
 }
 
 } // end namespace jitlink
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
index 22f17331503d93..a54f2a3abf59d1 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
@@ -107,11 +107,9 @@ MachOLinkGraphBuilder::getEndianness(const object::MachOObjectFile &Obj) {
 }
 
 Section &MachOLinkGraphBuilder::getCommonSection() {
-  if (!CommonSection) {
-    auto Prot = static_cast<sys::Memory::ProtectionFlags>(
-        sys::Memory::MF_READ | sys::Memory::MF_WRITE);
-    CommonSection = &G->createSection(CommonSectionName, Prot);
-  }
+  if (!CommonSection)
+    CommonSection =
+        &G->createSection(CommonSectionName, MemProt::Read | MemProt::Write);
   return *CommonSection;
 }
 
@@ -176,13 +174,11 @@ Error MachOLinkGraphBuilder::createNormalizedSections() {
     // Get prot flags.
     // FIXME: Make sure this test is correct (it's probably missing cases
     // as-is).
-    sys::Memory::ProtectionFlags Prot;
+    MemProt Prot;
     if (NSec.Flags & MachO::S_ATTR_PURE_INSTRUCTIONS)
-      Prot = static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
-                                                       sys::Memory::MF_EXEC);
+      Prot = MemProt::Read | MemProt::Exec;
     else
-      Prot = static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
-                                                       sys::Memory::MF_WRITE);
+      Prot = MemProt::Read | MemProt::Write;
 
     if (!isDebugSection(NSec)) {
       auto FullyQualifiedName =
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp b/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
index 8a2c7e527aa050..bf81fc4f8db9c2 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
@@ -457,16 +457,14 @@ class PerGraphGOTAndPLTStubsBuilder_MachO_arm64
 private:
   Section &getGOTSection() {
     if (!GOTSection)
-      GOTSection = &G.createSection("$__GOT", sys::Memory::MF_READ);
+      GOTSection = &G.createSection("$__GOT", MemProt::Read);
     return *GOTSection;
   }
 
   Section &getStubsSection() {
-    if (!StubsSection) {
-      auto StubsProt = static_cast<sys::Memory::ProtectionFlags>(
-          sys::Memory::MF_READ | sys::Memory::MF_EXEC);
-      StubsSection = &G.createSection("$__STUBS", StubsProt);
-    }
+    if (!StubsSection)
+      StubsSection =
+          &G.createSection("$__STUBS", MemProt::Read | MemProt::Exec);
     return *StubsSection;
   }
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp b/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
index b860816a889d3f..40ded07fae6a5a 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
@@ -479,16 +479,14 @@ class PerGraphGOTAndPLTStubsBuilder_MachO_x86_64
 private:
   Section &getGOTSection() {
     if (!GOTSection)
-      GOTSection = &G.createSection("$__GOT", sys::Memory::MF_READ);
+      GOTSection = &G.createSection("$__GOT", MemProt::Read);
     return *GOTSection;
   }
 
   Section &getStubsSection() {
-    if (!StubsSection) {
-      auto StubsProt = static_cast<sys::Memory::ProtectionFlags>(
-          sys::Memory::MF_READ | sys::Memory::MF_EXEC);
-      StubsSection = &G.createSection("$__STUBS", StubsProt);
-    }
+    if (!StubsSection)
+      StubsSection =
+          &G.createSection("$__STUBS", MemProt::Read | MemProt::Exec);
     return *StubsSection;
   }
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/MemoryFlags.cpp b/llvm/lib/ExecutionEngine/JITLink/MemoryFlags.cpp
new file mode 100644
index 00000000000000..b73a310b2910dd
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/JITLink/MemoryFlags.cpp
@@ -0,0 +1,33 @@
+//===------------- MemoryFlags.cpp - Memory allocation flags --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/JITLink/MemoryFlags.h"
+
+#define DEBUG_TYPE "jitlink"
+
+namespace llvm {
+namespace jitlink {
+
+raw_ostream &operator<<(raw_ostream &OS, MemProt MP) {
+  return OS << (((MP & MemProt::Read) != MemProt::None) ? 'R' : '-')
+            << (((MP & MemProt::Write) != MemProt::None) ? 'W' : '-')
+            << (((MP & MemProt::Exec) != MemProt::None) ? 'X' : '-');
+}
+
+raw_ostream &operator<<(raw_ostream &OS, MemDeallocPolicy MDP) {
+  return OS << (MDP == MemDeallocPolicy::Standard ? "standard" : "finalize");
+}
+
+raw_ostream &operator<<(raw_ostream &OS, AllocGroup AG) {
+  return OS << '(' << AG.getMemProt() << ", " << AG.getMemDeallocPolicy()
+            << ')';
+}
+
+} // end namespace jitlink
+} // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/Orc/DebugObjectManagerPlugin.cpp b/llvm/lib/ExecutionEngine/Orc/DebugObjectManagerPlugin.cpp
index 36efc744bf3076..fcfe389f82a815 100644
--- a/llvm/lib/ExecutionEngine/Orc/DebugObjectManagerPlugin.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/DebugObjectManagerPlugin.cpp
@@ -1,10 +1,15 @@
-//===---- DebugObjectManagerPlugin.h - JITLink debug objects ---*- C++ -*-===//
+//===------- DebugObjectManagerPlugin.cpp - JITLink debug objects ---------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
+//
+// FIXME: Update Plugin to poke the debug object into a new JITLink section,
+//        rather than creating a new allocation.
+//
+//===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/Orc/DebugObjectManagerPlugin.h"
 
@@ -108,70 +113,77 @@ void ELFDebugObjectSection<ELFT>::dump(raw_ostream &OS, StringRef Name) {
   }
 }
 
-static constexpr sys::Memory::ProtectionFlags ReadOnly =
-    static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ);
-
 enum class Requirement {
   // Request final target memory load-addresses for all sections.
   ReportFinalSectionLoadAddresses,
 };
 
-/// The plugin creates a debug object from JITLinkContext when JITLink starts
-/// processing the corresponding LinkGraph. It provides access to the pass
-/// configuration of the LinkGraph and calls the finalization function, once
-/// the resulting link artifact was emitted.
+/// The plugin creates a debug object from when JITLink starts processing the
+/// corresponding LinkGraph. It provides access to the pass configuration of
+/// the LinkGraph and calls the finalization function, once the resulting link
+/// artifact was emitted.
 ///
 class DebugObject {
 public:
-  DebugObject(JITLinkContext &Ctx, ExecutionSession &ES) : Ctx(Ctx), ES(ES) {}
+  DebugObject(JITLinkMemoryManager &MemMgr, const JITLinkDylib *JD,
+              ExecutionSession &ES)
+      : MemMgr(MemMgr), JD(JD), ES(ES) {}
 
   void set(Requirement Req) { Reqs.insert(Req); }
   bool has(Requirement Req) const { return Reqs.count(Req) > 0; }
 
-  using FinalizeContinuation = std::function<void(Expected<sys::MemoryBlock>)>;
+  using FinalizeContinuation = std::function<void(Expected<ExecutorAddrRange>)>;
+
   void finalizeAsync(FinalizeContinuation OnFinalize);
 
   virtual ~DebugObject() {
-    if (Alloc)
-      if (Error Err = Alloc->deallocate())
+    if (Alloc) {
+      std::vector<FinalizedAlloc> Allocs;
+      Allocs.push_back(std::move(Alloc));
+      if (Error Err = MemMgr.deallocate(std::move(Allocs)))
         ES.reportError(std::move(Err));
+    }
   }
 
   virtual void reportSectionTargetMemoryRange(StringRef Name,
                                               SectionRange TargetMem) {}
 
 protected:
-  using Allocation = JITLinkMemoryManager::Allocation;
+  using InFlightAlloc = JITLinkMemoryManager::InFlightAlloc;
+  using FinalizedAlloc = JITLinkMemoryManager::FinalizedAlloc;
 
-  virtual Expected<std::unique_ptr<Allocation>>
-  finalizeWorkingMemory(JITLinkContext &Ctx) = 0;
+  virtual Expected<SimpleSegmentAlloc> finalizeWorkingMemory() = 0;
+
+  JITLinkMemoryManager &MemMgr;
+  const JITLinkDylib *JD = nullptr;
 
 private:
-  JITLinkContext &Ctx;
   ExecutionSession &ES;
   std::set<Requirement> Reqs;
-  std::unique_ptr<Allocation> Alloc{nullptr};
+  FinalizedAlloc Alloc;
 };
 
 // Finalize working memory and take ownership of the resulting allocation. Start
 // copying memory over to the target and pass on the result once we're done.
 // Ownership of the allocation remains with us for the rest of our lifetime.
 void DebugObject::finalizeAsync(FinalizeContinuation OnFinalize) {
-  assert(Alloc == nullptr && "Cannot finalize more than once");
-
-  auto AllocOrErr = finalizeWorkingMemory(Ctx);
-  if (!AllocOrErr)
-    OnFinalize(AllocOrErr.takeError());
-  Alloc = std::move(*AllocOrErr);
-
-  Alloc->finalizeAsync([this, OnFinalize](Error Err) {
-    if (Err)
-      OnFinalize(std::move(Err));
-    else
-      OnFinalize(sys::MemoryBlock(
-          jitTargetAddressToPointer<void *>(Alloc->getTargetMemory(ReadOnly)),
-          Alloc->getWorkingMemory(ReadOnly).size()));
-  });
+  assert(!Alloc && "Cannot finalize more than once");
+
+  if (auto SimpleSegAlloc = finalizeWorkingMemory()) {
+    auto ROSeg = SimpleSegAlloc->getSegInfo(MemProt::Read);
+    ExecutorAddrRange DebugObjRange(ExecutorAddr(ROSeg.Addr),
+                                    ExecutorAddrDiff(ROSeg.WorkingMem.size()));
+    SimpleSegAlloc->finalize(
+        [this, DebugObjRange,
+         OnFinalize = std::move(OnFinalize)](Expected<FinalizedAlloc> FA) {
+          if (FA) {
+            Alloc = std::move(*FA);
+            OnFinalize(DebugObjRange);
+          } else
+            OnFinalize(FA.takeError());
+        });
+  } else
+    OnFinalize(SimpleSegAlloc.takeError());
 }
 
 /// The current implementation of ELFDebugObject replicates the approach used in
@@ -190,8 +202,7 @@ class ELFDebugObject : public DebugObject {
   StringRef getBuffer() const { return Buffer->getMemBufferRef().getBuffer(); }
 
 protected:
-  Expected<std::unique_ptr<Allocation>>
-  finalizeWorkingMemory(JITLinkContext &Ctx) override;
+  Expected<SimpleSegmentAlloc> finalizeWorkingMemory() override;
 
   template <typename ELFT>
   Error recordSection(StringRef Name,
@@ -201,15 +212,16 @@ class ELFDebugObject : public DebugObject {
 private:
   template <typename ELFT>
   static Expected<std::unique_ptr<ELFDebugObject>>
-  CreateArchType(MemoryBufferRef Buffer, JITLinkContext &Ctx,
-                 ExecutionSession &ES);
+  CreateArchType(MemoryBufferRef Buffer, JITLinkMemoryManager &MemMgr,
+                 const JITLinkDylib *JD, ExecutionSession &ES);
 
   static std::unique_ptr<WritableMemoryBuffer>
   CopyBuffer(MemoryBufferRef Buffer, Error &Err);
 
   ELFDebugObject(std::unique_ptr<WritableMemoryBuffer> Buffer,
-                 JITLinkContext &Ctx, ExecutionSession &ES)
-      : DebugObject(Ctx, ES), Buffer(std::move(Buffer)) {
+                 JITLinkMemoryManager &MemMgr, const JITLinkDylib *JD,
+                 ExecutionSession &ES)
+      : DebugObject(MemMgr, JD, ES), Buffer(std::move(Buffer)) {
     set(Requirement::ReportFinalSectionLoadAddresses);
   }
 
@@ -244,13 +256,14 @@ ELFDebugObject::CopyBuffer(MemoryBufferRef Buffer, Error &Err) {
 
 template <typename ELFT>
 Expected<std::unique_ptr<ELFDebugObject>>
-ELFDebugObject::CreateArchType(MemoryBufferRef Buffer, JITLinkContext &Ctx,
-                               ExecutionSession &ES) {
+ELFDebugObject::CreateArchType(MemoryBufferRef Buffer,
+                               JITLinkMemoryManager &MemMgr,
+                               const JITLinkDylib *JD, ExecutionSession &ES) {
   using SectionHeader = typename ELFT::Shdr;
 
   Error Err = Error::success();
   std::unique_ptr<ELFDebugObject> DebugObj(
-      new ELFDebugObject(CopyBuffer(Buffer, Err), Ctx, ES));
+      new ELFDebugObject(CopyBuffer(Buffer, Err), MemMgr, JD, ES));
   if (Err)
     return std::move(Err);
 
@@ -299,23 +312,26 @@ ELFDebugObject::Create(MemoryBufferRef Buffer, JITLinkContext &Ctx,
 
   if (Class == ELF::ELFCLASS32) {
     if (Endian == ELF::ELFDATA2LSB)
-      return CreateArchType<ELF32LE>(Buffer, Ctx, ES);
+      return CreateArchType<ELF32LE>(Buffer, Ctx.getMemoryManager(),
+                                     Ctx.getJITLinkDylib(), ES);
     if (Endian == ELF::ELFDATA2MSB)
-      return CreateArchType<ELF32BE>(Buffer, Ctx, ES);
+      return CreateArchType<ELF32BE>(Buffer, Ctx.getMemoryManager(),
+                                     Ctx.getJITLinkDylib(), ES);
     return nullptr;
   }
   if (Class == ELF::ELFCLASS64) {
     if (Endian == ELF::ELFDATA2LSB)
-      return CreateArchType<ELF64LE>(Buffer, Ctx, ES);
+      return CreateArchType<ELF64LE>(Buffer, Ctx.getMemoryManager(),
+                                     Ctx.getJITLinkDylib(), ES);
     if (Endian == ELF::ELFDATA2MSB)
-      return CreateArchType<ELF64BE>(Buffer, Ctx, ES);
+      return CreateArchType<ELF64BE>(Buffer, Ctx.getMemoryManager(),
+                                     Ctx.getJITLinkDylib(), ES);
     return nullptr;
   }
   return nullptr;
 }
 
-Expected<std::unique_ptr<DebugObject::Allocation>>
-ELFDebugObject::finalizeWorkingMemory(JITLinkContext &Ctx) {
+Expected<SimpleSegmentAlloc> ELFDebugObject::finalizeWorkingMemory() {
   LLVM_DEBUG({
     dbgs() << "Section load-addresses in debug object for \""
            << Buffer->getBufferIdentifier() << "\":\n";
@@ -324,28 +340,21 @@ ELFDebugObject::finalizeWorkingMemory(JITLinkContext &Ctx) {
   });
 
   // TODO: This works, but what actual alignment requirements do we have?
-  unsigned Alignment = sys::Process::getPageSizeEstimate();
-  JITLinkMemoryManager &MemMgr = Ctx.getMemoryManager();
-  const JITLinkDylib *JD = Ctx.getJITLinkDylib();
+  unsigned PageSize = sys::Process::getPageSizeEstimate();
   size_t Size = Buffer->getBufferSize();
 
   // Allocate working memory for debug object in read-only segment.
-  JITLinkMemoryManager::SegmentsRequestMap SingleReadOnlySegment;
-  SingleReadOnlySegment[ReadOnly] =
-      JITLinkMemoryManager::SegmentRequest(Alignment, Size, 0);
-
-  auto AllocOrErr = MemMgr.allocate(JD, SingleReadOnlySegment);
-  if (!AllocOrErr)
-    return AllocOrErr.takeError();
+  auto Alloc = SimpleSegmentAlloc::Create(
+      MemMgr, JD, {{MemProt::Read, {Size, Align(PageSize)}}});
+  if (!Alloc)
+    return Alloc;
 
   // Initialize working memory with a copy of our object buffer.
-  // TODO: Use our buffer as working memory directly.
-  std::unique_ptr<Allocation> Alloc = std::move(*AllocOrErr);
-  MutableArrayRef<char> WorkingMem = Alloc->getWorkingMemory(ReadOnly);
-  memcpy(WorkingMem.data(), Buffer->getBufferStart(), Size);
+  auto SegInfo = Alloc->getSegInfo(MemProt::Read);
+  memcpy(SegInfo.WorkingMem.data(), Buffer->getBufferStart(), Size);
   Buffer.reset();
 
-  return std::move(Alloc);
+  return Alloc;
 }
 
 void ELFDebugObject::reportSectionTargetMemoryRange(StringRef Name,
@@ -447,7 +456,7 @@ Error DebugObjectManagerPlugin::notifyEmitted(
   std::future<MSVCPError> FinalizeErr = FinalizePromise.get_future();
 
   It->second->finalizeAsync(
-      [this, &FinalizePromise, &MR](Expected<sys::MemoryBlock> TargetMem) {
+      [this, &FinalizePromise, &MR](Expected<ExecutorAddrRange> TargetMem) {
         // Any failure here will fail materialization.
         if (!TargetMem) {
           FinalizePromise.set_value(TargetMem.takeError());
diff --git a/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp b/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp
index 79c602d0b01ec0..88d4cf9f58eeb0 100644
--- a/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp
@@ -56,7 +56,7 @@ class DSOHandleMaterializationUnit : public MaterializationUnit {
         "<DSOHandleMU>", TT, PointerSize, Endianness,
         jitlink::getGenericEdgeKindName);
     auto &DSOHandleSection =
-        G->createSection(".data.__dso_handle", sys::Memory::MF_READ);
+        G->createSection(".data.__dso_handle", jitlink::MemProt::Read);
     auto &DSOHandleBlock = G->createContentBlock(
         DSOHandleSection, getDSOHandleContent(PointerSize), 0, 8, 0);
     auto &DSOHandleSymbol = G->addDefinedSymbol(
diff --git a/llvm/lib/ExecutionEngine/Orc/EPCDebugObjectRegistrar.cpp b/llvm/lib/ExecutionEngine/Orc/EPCDebugObjectRegistrar.cpp
index e1639a82b5d96c..f3fe0555fa75b7 100644
--- a/llvm/lib/ExecutionEngine/Orc/EPCDebugObjectRegistrar.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/EPCDebugObjectRegistrar.cpp
@@ -43,10 +43,9 @@ createJITLoaderGDBRegistrar(ExecutionSession &ES) {
       ES, ExecutorAddr((*Result)[0][0]));
 }
 
-Error EPCDebugObjectRegistrar::registerDebugObject(sys::MemoryBlock TargetMem) {
-  return ES.callSPSWrapper<void(SPSExecutorAddr, uint64_t)>(
-      RegisterFn, ExecutorAddr::fromPtr(TargetMem.base()),
-      static_cast<uint64_t>(TargetMem.allocatedSize()));
+Error EPCDebugObjectRegistrar::registerDebugObject(
+    ExecutorAddrRange TargetMem) {
+  return ES.callSPSWrapper<void(SPSExecutorAddrRange)>(RegisterFn, TargetMem);
 }
 
 } // namespace orc
diff --git a/llvm/lib/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManager.cpp b/llvm/lib/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManager.cpp
index 234c0852a01311..94568371bb8827 100644
--- a/llvm/lib/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManager.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManager.cpp
@@ -7,132 +7,168 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManager.h"
+
+#include "llvm/ExecutionEngine/JITLink/JITLink.h"
 #include "llvm/ExecutionEngine/Orc/LookupAndRecordAddrs.h"
 #include "llvm/ExecutionEngine/Orc/Shared/OrcRTBridge.h"
 
 #include <limits>
 
+using namespace llvm::jitlink;
+
 namespace llvm {
 namespace orc {
 
-class EPCGenericJITLinkMemoryManager::Alloc
-    : public jitlink::JITLinkMemoryManager::Allocation {
+class EPCGenericJITLinkMemoryManager::InFlightAlloc
+    : public jitlink::JITLinkMemoryManager::InFlightAlloc {
 public:
   struct SegInfo {
     char *WorkingMem = nullptr;
-    ExecutorAddr TargetAddr;
+    ExecutorAddr Addr;
     uint64_t ContentSize = 0;
     uint64_t ZeroFillSize = 0;
   };
-  using SegInfoMap = DenseMap<unsigned, SegInfo>;
-
-  Alloc(EPCGenericJITLinkMemoryManager &Parent, ExecutorAddr TargetAddr,
-        std::unique_ptr<char[]> WorkingBuffer, SegInfoMap Segs)
-      : Parent(Parent), TargetAddr(TargetAddr),
-        WorkingBuffer(std::move(WorkingBuffer)), Segs(std::move(Segs)) {}
-
-  MutableArrayRef<char> getWorkingMemory(ProtectionFlags Seg) override {
-    auto I = Segs.find(Seg);
-    assert(I != Segs.end() && "No allocation for seg");
-    assert(I->second.ContentSize <= std::numeric_limits<size_t>::max());
-    return {I->second.WorkingMem, static_cast<size_t>(I->second.ContentSize)};
-  }
+  using SegInfoMap = AllocGroupSmallMap<SegInfo>;
 
-  JITTargetAddress getTargetMemory(ProtectionFlags Seg) override {
-    auto I = Segs.find(Seg);
-    assert(I != Segs.end() && "No allocation for seg");
-    return I->second.TargetAddr.getValue();
-  }
+  InFlightAlloc(EPCGenericJITLinkMemoryManager &Parent, LinkGraph &G,
+                ExecutorAddr AllocAddr, SegInfoMap Segs)
+      : Parent(Parent), G(G), AllocAddr(AllocAddr), Segs(std::move(Segs)) {}
 
-  void finalizeAsync(FinalizeContinuation OnFinalize) override {
-    char *WorkingMem = WorkingBuffer.get();
+  void finalize(OnFinalizedFunction OnFinalize) override {
     tpctypes::FinalizeRequest FR;
     for (auto &KV : Segs) {
       assert(KV.second.ContentSize <= std::numeric_limits<size_t>::max());
       FR.Segments.push_back(tpctypes::SegFinalizeRequest{
           tpctypes::toWireProtectionFlags(
-              static_cast<sys::Memory::ProtectionFlags>(KV.first)),
-          KV.second.TargetAddr,
+              toSysMemoryProtectionFlags(KV.first.getMemProt())),
+          KV.second.Addr,
           alignTo(KV.second.ContentSize + KV.second.ZeroFillSize,
                   Parent.EPC.getPageSize()),
-          {WorkingMem, static_cast<size_t>(KV.second.ContentSize)}});
-      WorkingMem += KV.second.ContentSize;
+          {KV.second.WorkingMem, static_cast<size_t>(KV.second.ContentSize)}});
     }
+
+    // Transfer allocation actions.
+    // FIXME: Merge JITLink and ORC SupportFunctionCall and Action list types,
+    //        turn this into a std::swap.
+    FR.Actions.reserve(G.allocActions().size());
+    for (auto &ActPair : G.allocActions())
+      FR.Actions.push_back(
+          {{ExecutorAddr(ActPair.Finalize.FnAddr),
+            ExecutorAddr(ActPair.Finalize.CtxAddr), ActPair.Finalize.CtxSize},
+           {ExecutorAddr(ActPair.Dealloc.FnAddr),
+            ExecutorAddr(ActPair.Dealloc.CtxAddr), ActPair.Dealloc.CtxSize}});
+    G.allocActions().clear();
+
     Parent.EPC.callSPSWrapperAsync<
         rt::SPSSimpleExecutorMemoryManagerFinalizeSignature>(
         Parent.SAs.Finalize,
-        [OnFinalize = std::move(OnFinalize)](Error SerializationErr,
-                                             Error FinalizeErr) {
+        [OnFinalize = std::move(OnFinalize), AllocAddr = this->AllocAddr](
+            Error SerializationErr, Error FinalizeErr) mutable {
+          // FIXME: Release abandoned alloc.
           if (SerializationErr) {
             cantFail(std::move(FinalizeErr));
             OnFinalize(std::move(SerializationErr));
-          } else
+          } else if (FinalizeErr)
             OnFinalize(std::move(FinalizeErr));
+          else
+            OnFinalize(FinalizedAlloc(AllocAddr.getValue()));
         },
         Parent.SAs.Allocator, std::move(FR));
   }
 
-  Error deallocate() override {
-    Error Err = Error::success();
-    if (auto E2 = Parent.EPC.callSPSWrapper<
-                  rt::SPSSimpleExecutorMemoryManagerDeallocateSignature>(
-            Parent.SAs.Deallocate, Err, Parent.SAs.Allocator,
-            ArrayRef<ExecutorAddr>(TargetAddr)))
-      return E2;
-    return Err;
+  void abandon(OnAbandonedFunction OnAbandoned) override {
+    // FIXME: Return memory to pool instead.
+    Parent.EPC.callSPSWrapperAsync<
+        rt::SPSSimpleExecutorMemoryManagerDeallocateSignature>(
+        Parent.SAs.Deallocate,
+        [OnAbandoned = std::move(OnAbandoned)](Error SerializationErr,
+                                               Error DeallocateErr) mutable {
+          if (SerializationErr) {
+            cantFail(std::move(DeallocateErr));
+            OnAbandoned(std::move(SerializationErr));
+          } else
+            OnAbandoned(std::move(DeallocateErr));
+        },
+        Parent.SAs.Allocator, ArrayRef<ExecutorAddr>(AllocAddr));
   }
 
 private:
   EPCGenericJITLinkMemoryManager &Parent;
-  ExecutorAddr TargetAddr;
-  std::unique_ptr<char[]> WorkingBuffer;
+  LinkGraph &G;
+  ExecutorAddr AllocAddr;
   SegInfoMap Segs;
 };
 
-Expected<std::unique_ptr<jitlink::JITLinkMemoryManager::Allocation>>
-EPCGenericJITLinkMemoryManager::allocate(const jitlink::JITLinkDylib *JD,
-                                         const SegmentsRequestMap &Request) {
-  Alloc::SegInfoMap Segs;
-  uint64_t AllocSize = 0;
-  size_t WorkingSize = 0;
-  for (auto &KV : Request) {
-    if (!isPowerOf2_64(KV.second.getAlignment()))
-      return make_error<StringError>("Alignment is not a power of two",
-                                     inconvertibleErrorCode());
-    if (KV.second.getAlignment() > EPC.getPageSize())
-      return make_error<StringError>("Alignment exceeds page size",
-                                     inconvertibleErrorCode());
-
-    auto &Seg = Segs[KV.first];
-    Seg.ContentSize = KV.second.getContentSize();
-    Seg.ZeroFillSize = KV.second.getZeroFillSize();
-    AllocSize += alignTo(Seg.ContentSize + Seg.ZeroFillSize, EPC.getPageSize());
-    WorkingSize += Seg.ContentSize;
-  }
+void EPCGenericJITLinkMemoryManager::allocate(const JITLinkDylib *JD,
+                                              LinkGraph &G,
+                                              OnAllocatedFunction OnAllocated) {
+  BasicLayout BL(G);
+
+  auto Pages = BL.getContiguousPageBasedLayoutSizes(EPC.getPageSize());
+  if (!Pages)
+    return OnAllocated(Pages.takeError());
+
+  EPC.callSPSWrapperAsync<rt::SPSSimpleExecutorMemoryManagerReserveSignature>(
+      SAs.Reserve,
+      [this, BL = std::move(BL), OnAllocated = std::move(OnAllocated)](
+          Error SerializationErr, Expected<ExecutorAddr> AllocAddr) mutable {
+        if (SerializationErr) {
+          cantFail(AllocAddr.takeError());
+          return OnAllocated(std::move(SerializationErr));
+        }
+        if (!AllocAddr)
+          return OnAllocated(AllocAddr.takeError());
+
+        completeAllocation(*AllocAddr, std::move(BL), std::move(OnAllocated));
+      },
+      SAs.Allocator, Pages->total());
+}
+
+void EPCGenericJITLinkMemoryManager::deallocate(
+    std::vector<FinalizedAlloc> Allocs, OnDeallocatedFunction OnDeallocated) {
+  EPC.callSPSWrapperAsync<
+      rt::SPSSimpleExecutorMemoryManagerDeallocateSignature>(
+      SAs.Deallocate,
+      [OnDeallocated = std::move(OnDeallocated)](Error SerErr,
+                                                 Error DeallocErr) mutable {
+        if (SerErr) {
+          cantFail(std::move(DeallocErr));
+          OnDeallocated(std::move(SerErr));
+        } else
+          OnDeallocated(std::move(DeallocErr));
+      },
+      SAs.Allocator, Allocs);
+  for (auto &A : Allocs)
+    A.release();
+}
 
-  std::unique_ptr<char[]> WorkingBuffer;
-  if (WorkingSize > 0)
-    WorkingBuffer = std::make_unique<char[]>(WorkingSize);
-  Expected<ExecutorAddr> TargetAllocAddr((ExecutorAddr()));
-  if (auto Err = EPC.callSPSWrapper<
-                 rt::SPSSimpleExecutorMemoryManagerReserveSignature>(
-          SAs.Reserve, TargetAllocAddr, SAs.Allocator, AllocSize))
-    return std::move(Err);
-  if (!TargetAllocAddr)
-    return TargetAllocAddr.takeError();
-
-  char *WorkingMem = WorkingBuffer.get();
-  JITTargetAddress SegAddr = TargetAllocAddr->getValue();
-  for (auto &KV : Segs) {
+void EPCGenericJITLinkMemoryManager::completeAllocation(
+    ExecutorAddr AllocAddr, BasicLayout BL, OnAllocatedFunction OnAllocated) {
+
+  InFlightAlloc::SegInfoMap SegInfos;
+
+  ExecutorAddr NextSegAddr = AllocAddr;
+  for (auto &KV : BL.segments()) {
+    const auto &AG = KV.first;
     auto &Seg = KV.second;
-    Seg.TargetAddr.setValue(SegAddr);
-    SegAddr += alignTo(Seg.ContentSize + Seg.ZeroFillSize, EPC.getPageSize());
-    Seg.WorkingMem = WorkingMem;
-    WorkingMem += Seg.ContentSize;
+
+    Seg.Addr = NextSegAddr.getValue();
+    KV.second.WorkingMem = BL.getGraph().allocateBuffer(Seg.ContentSize).data();
+    NextSegAddr += ExecutorAddrDiff(
+        alignTo(Seg.ContentSize + Seg.ZeroFillSize, EPC.getPageSize()));
+
+    auto &SegInfo = SegInfos[AG];
+    SegInfo.ContentSize = Seg.ContentSize;
+    SegInfo.ZeroFillSize = Seg.ZeroFillSize;
+    SegInfo.Addr = ExecutorAddr(Seg.Addr);
+    SegInfo.WorkingMem = Seg.WorkingMem;
   }
 
-  return std::make_unique<Alloc>(*this, *TargetAllocAddr,
-                                 std::move(WorkingBuffer), std::move(Segs));
+  if (auto Err = BL.apply())
+    return OnAllocated(std::move(Err));
+
+  OnAllocated(std::make_unique<InFlightAlloc>(*this, BL.getGraph(), AllocAddr,
+                                              std::move(SegInfos)));
 }
 
 } // end namespace orc
diff --git a/llvm/lib/ExecutionEngine/Orc/EPCIndirectionUtils.cpp b/llvm/lib/ExecutionEngine/Orc/EPCIndirectionUtils.cpp
index b9c70b0aeb3cb6..948d1d96aeff75 100644
--- a/llvm/lib/ExecutionEngine/Orc/EPCIndirectionUtils.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/EPCIndirectionUtils.cpp
@@ -43,12 +43,12 @@ class EPCTrampolinePool : public TrampolinePool {
 protected:
   Error grow() override;
 
-  using Allocation = jitlink::JITLinkMemoryManager::Allocation;
+  using FinalizedAlloc = jitlink::JITLinkMemoryManager::FinalizedAlloc;
 
   EPCIndirectionUtils &EPCIU;
   unsigned TrampolineSize = 0;
   unsigned TrampolinesPerPage = 0;
-  std::vector<std::unique_ptr<Allocation>> TrampolineBlocks;
+  std::vector<FinalizedAlloc> TrampolineBlocks;
 };
 
 class EPCIndirectStubsManager : public IndirectStubsManager,
@@ -89,12 +89,19 @@ EPCTrampolinePool::EPCTrampolinePool(EPCIndirectionUtils &EPCIU)
 
 Error EPCTrampolinePool::deallocatePool() {
   Error Err = Error::success();
-  for (auto &Alloc : TrampolineBlocks)
-    Err = joinErrors(std::move(Err), Alloc->deallocate());
-  return Err;
+  std::promise<MSVCPError> DeallocResultP;
+  auto DeallocResultF = DeallocResultP.get_future();
+
+  EPCIU.getExecutorProcessControl().getMemMgr().deallocate(
+      std::move(TrampolineBlocks),
+      [&](Error Err) { DeallocResultP.set_value(std::move(Err)); });
+
+  return DeallocResultF.get();
 }
 
 Error EPCTrampolinePool::grow() {
+  using namespace jitlink;
+
   assert(AvailableTrampolines.empty() &&
          "Grow called with trampolines still available");
 
@@ -102,34 +109,26 @@ Error EPCTrampolinePool::grow() {
   assert(ResolverAddress && "Resolver address can not be null");
 
   auto &EPC = EPCIU.getExecutorProcessControl();
-  constexpr auto TrampolinePagePermissions =
-      static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
-                                                sys::Memory::MF_EXEC);
   auto PageSize = EPC.getPageSize();
-  jitlink::JITLinkMemoryManager::SegmentsRequestMap Request;
-  Request[TrampolinePagePermissions] = {PageSize, static_cast<size_t>(PageSize),
-                                        0};
-  auto Alloc = EPC.getMemMgr().allocate(nullptr, Request);
-
+  auto Alloc = SimpleSegmentAlloc::Create(
+      EPC.getMemMgr(), nullptr,
+      {{MemProt::Read | MemProt::Exec, {PageSize, Align(PageSize)}}});
   if (!Alloc)
     return Alloc.takeError();
 
   unsigned NumTrampolines = TrampolinesPerPage;
 
-  auto WorkingMemory = (*Alloc)->getWorkingMemory(TrampolinePagePermissions);
-  auto TargetAddress = (*Alloc)->getTargetMemory(TrampolinePagePermissions);
-
-  EPCIU.getABISupport().writeTrampolines(WorkingMemory.data(), TargetAddress,
-                                         ResolverAddress, NumTrampolines);
-
-  auto TargetAddr = (*Alloc)->getTargetMemory(TrampolinePagePermissions);
+  auto SegInfo = Alloc->getSegInfo(MemProt::Read | MemProt::Exec);
+  EPCIU.getABISupport().writeTrampolines(
+      SegInfo.WorkingMem.data(), SegInfo.Addr, ResolverAddress, NumTrampolines);
   for (unsigned I = 0; I < NumTrampolines; ++I)
-    AvailableTrampolines.push_back(TargetAddr + (I * TrampolineSize));
+    AvailableTrampolines.push_back(SegInfo.Addr + (I * TrampolineSize));
 
-  if (auto Err = (*Alloc)->finalize())
-    return Err;
+  auto FA = Alloc->finalize();
+  if (!FA)
+    return FA.takeError();
 
-  TrampolineBlocks.push_back(std::move(*Alloc));
+  TrampolineBlocks.push_back(std::move(*FA));
 
   return Error::success();
 }
@@ -267,17 +266,17 @@ EPCIndirectionUtils::Create(ExecutorProcessControl &EPC) {
 }
 
 Error EPCIndirectionUtils::cleanup() {
-  Error Err = Error::success();
 
-  for (auto &A : IndirectStubAllocs)
-    Err = joinErrors(std::move(Err), A->deallocate());
+  auto &MemMgr = EPC.getMemMgr();
+  auto Err = MemMgr.deallocate(std::move(IndirectStubAllocs));
 
   if (TP)
     Err = joinErrors(std::move(Err),
                      static_cast<EPCTrampolinePool &>(*TP).deallocatePool());
 
   if (ResolverBlock)
-    Err = joinErrors(std::move(Err), ResolverBlock->deallocate());
+    Err =
+        joinErrors(std::move(Err), MemMgr.deallocate(std::move(ResolverBlock)));
 
   return Err;
 }
@@ -285,29 +284,29 @@ Error EPCIndirectionUtils::cleanup() {
 Expected<JITTargetAddress>
 EPCIndirectionUtils::writeResolverBlock(JITTargetAddress ReentryFnAddr,
                                         JITTargetAddress ReentryCtxAddr) {
+  using namespace jitlink;
+
   assert(ABI && "ABI can not be null");
-  constexpr auto ResolverBlockPermissions =
-      static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
-                                                sys::Memory::MF_EXEC);
   auto ResolverSize = ABI->getResolverCodeSize();
 
-  jitlink::JITLinkMemoryManager::SegmentsRequestMap Request;
-  Request[ResolverBlockPermissions] = {EPC.getPageSize(),
-                                       static_cast<size_t>(ResolverSize), 0};
-  auto Alloc = EPC.getMemMgr().allocate(nullptr, Request);
+  auto Alloc =
+      SimpleSegmentAlloc::Create(EPC.getMemMgr(), nullptr,
+                                 {{MemProt::Read | MemProt::Exec,
+                                   {ResolverSize, Align(EPC.getPageSize())}}});
+
   if (!Alloc)
     return Alloc.takeError();
 
-  auto WorkingMemory = (*Alloc)->getWorkingMemory(ResolverBlockPermissions);
-  ResolverBlockAddr = (*Alloc)->getTargetMemory(ResolverBlockPermissions);
-  ABI->writeResolverCode(WorkingMemory.data(), ResolverBlockAddr, ReentryFnAddr,
+  auto SegInfo = Alloc->getSegInfo(MemProt::Read | MemProt::Exec);
+  ABI->writeResolverCode(SegInfo.WorkingMem.data(), SegInfo.Addr, ReentryFnAddr,
                          ReentryCtxAddr);
 
-  if (auto Err = (*Alloc)->finalize())
-    return std::move(Err);
+  auto FA = Alloc->finalize();
+  if (!FA)
+    return FA.takeError();
 
-  ResolverBlock = std::move(*Alloc);
-  return ResolverBlockAddr;
+  ResolverBlock = std::move(*FA);
+  return SegInfo.Addr;
 }
 
 std::unique_ptr<IndirectStubsManager>
@@ -341,6 +340,7 @@ EPCIndirectionUtils::EPCIndirectionUtils(ExecutorProcessControl &EPC,
 
 Expected<EPCIndirectionUtils::IndirectStubInfoVector>
 EPCIndirectionUtils::getIndirectStubs(unsigned NumStubs) {
+  using namespace jitlink;
 
   std::lock_guard<std::mutex> Lock(EPCUIMutex);
 
@@ -350,42 +350,40 @@ EPCIndirectionUtils::getIndirectStubs(unsigned NumStubs) {
     auto PageSize = EPC.getPageSize();
     auto StubBytes = alignTo(NumStubsToAllocate * ABI->getStubSize(), PageSize);
     NumStubsToAllocate = StubBytes / ABI->getStubSize();
-    auto PointerBytes =
+    auto PtrBytes =
         alignTo(NumStubsToAllocate * ABI->getPointerSize(), PageSize);
 
-    constexpr auto StubPagePermissions =
-        static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
-                                                  sys::Memory::MF_EXEC);
-    constexpr auto PointerPagePermissions =
-        static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
-                                                  sys::Memory::MF_WRITE);
-
-    jitlink::JITLinkMemoryManager::SegmentsRequestMap Request;
-    Request[StubPagePermissions] = {PageSize, static_cast<size_t>(StubBytes),
-                                    0};
-    Request[PointerPagePermissions] = {PageSize, 0, PointerBytes};
-    auto Alloc = EPC.getMemMgr().allocate(nullptr, Request);
+    auto StubProt = MemProt::Read | MemProt::Exec;
+    auto PtrProt = MemProt::Read | MemProt::Write;
+
+    auto Alloc = SimpleSegmentAlloc::Create(
+        EPC.getMemMgr(), nullptr,
+        {{StubProt, {static_cast<size_t>(StubBytes), Align(PageSize)}},
+         {PtrProt, {PtrBytes, Align(PageSize)}}});
+
     if (!Alloc)
       return Alloc.takeError();
 
-    auto StubTargetAddr = (*Alloc)->getTargetMemory(StubPagePermissions);
-    auto PointerTargetAddr = (*Alloc)->getTargetMemory(PointerPagePermissions);
+    auto StubSeg = Alloc->getSegInfo(StubProt);
+    auto PtrSeg = Alloc->getSegInfo(PtrProt);
+
+    ABI->writeIndirectStubsBlock(StubSeg.WorkingMem.data(), StubSeg.Addr,
+                                 PtrSeg.Addr, NumStubsToAllocate);
 
-    ABI->writeIndirectStubsBlock(
-        (*Alloc)->getWorkingMemory(StubPagePermissions).data(), StubTargetAddr,
-        PointerTargetAddr, NumStubsToAllocate);
+    auto FA = Alloc->finalize();
+    if (!FA)
+      return FA.takeError();
 
-    if (auto Err = (*Alloc)->finalize())
-      return std::move(Err);
+    IndirectStubAllocs.push_back(std::move(*FA));
 
+    auto StubExecutorAddr = StubSeg.Addr;
+    auto PtrExecutorAddr = PtrSeg.Addr;
     for (unsigned I = 0; I != NumStubsToAllocate; ++I) {
       AvailableIndirectStubs.push_back(
-          IndirectStubInfo(StubTargetAddr, PointerTargetAddr));
-      StubTargetAddr += ABI->getStubSize();
-      PointerTargetAddr += ABI->getPointerSize();
+          IndirectStubInfo(StubExecutorAddr, PtrExecutorAddr));
+      StubExecutorAddr += ABI->getStubSize();
+      PtrExecutorAddr += ABI->getPointerSize();
     }
-
-    IndirectStubAllocs.push_back(std::move(*Alloc));
   }
 
   assert(NumStubs <= AvailableIndirectStubs.size() &&
diff --git a/llvm/lib/ExecutionEngine/Orc/ExecutorProcessControl.cpp b/llvm/lib/ExecutionEngine/Orc/ExecutorProcessControl.cpp
index 6fb8b52e581fac..014538759b8afb 100644
--- a/llvm/lib/ExecutionEngine/Orc/ExecutorProcessControl.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ExecutorProcessControl.cpp
@@ -31,7 +31,8 @@ SelfExecutorProcessControl::SelfExecutorProcessControl(
 
   OwnedMemMgr = std::move(MemMgr);
   if (!OwnedMemMgr)
-    OwnedMemMgr = std::make_unique<jitlink::InProcessMemoryManager>();
+    OwnedMemMgr = std::make_unique<jitlink::InProcessMemoryManager>(
+        sys::Process::getPageSizeEstimate());
 
   this->TargetTriple = std::move(TargetTriple);
   this->PageSize = PageSize;
diff --git a/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp b/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
index 1705010df34628..e34626297d12fd 100644
--- a/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
@@ -53,7 +53,7 @@ class MachOHeaderMaterializationUnit : public MaterializationUnit {
     auto G = std::make_unique<jitlink::LinkGraph>(
         "<MachOHeaderMU>", TT, PointerSize, Endianness,
         jitlink::getGenericEdgeKindName);
-    auto &HeaderSection = G->createSection("__header", sys::Memory::MF_READ);
+    auto &HeaderSection = G->createSection("__header", jitlink::MemProt::Read);
     auto &HeaderBlock = createHeaderBlock(*G, HeaderSection);
 
     // Init symbol is header-start symbol.
diff --git a/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp b/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
index 40d4f199ff658b..22a6425c5510ff 100644
--- a/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
@@ -306,8 +306,7 @@ class ObjectLinkingLayerJITLinkContext final : public JITLinkContext {
     return Error::success();
   }
 
-  void notifyFinalized(
-      std::unique_ptr<JITLinkMemoryManager::Allocation> A) override {
+  void notifyFinalized(JITLinkMemoryManager::FinalizedAlloc A) override {
     if (auto Err = Layer.notifyEmitted(*MR, std::move(A))) {
       Layer.getExecutionSession().reportError(std::move(Err));
       MR->failMaterialization();
@@ -680,7 +679,7 @@ void ObjectLinkingLayer::notifyLoaded(MaterializationResponsibility &MR) {
 }
 
 Error ObjectLinkingLayer::notifyEmitted(MaterializationResponsibility &MR,
-                                        AllocPtr Alloc) {
+                                        FinalizedAlloc FA) {
   Error Err = Error::success();
   for (auto &P : Plugins)
     Err = joinErrors(std::move(Err), P->notifyEmitted(MR));
@@ -689,17 +688,20 @@ Error ObjectLinkingLayer::notifyEmitted(MaterializationResponsibility &MR,
     return Err;
 
   return MR.withResourceKeyDo(
-      [&](ResourceKey K) { Allocs[K].push_back(std::move(Alloc)); });
+      [&](ResourceKey K) { Allocs[K].push_back(std::move(FA)); });
 }
 
 Error ObjectLinkingLayer::handleRemoveResources(ResourceKey K) {
 
-  Error Err = Error::success();
-
-  for (auto &P : Plugins)
-    Err = joinErrors(std::move(Err), P->notifyRemovingResources(K));
+  {
+    Error Err = Error::success();
+    for (auto &P : Plugins)
+      Err = joinErrors(std::move(Err), P->notifyRemovingResources(K));
+    if (Err)
+      return Err;
+  }
 
-  std::vector<AllocPtr> AllocsToRemove;
+  std::vector<FinalizedAlloc> AllocsToRemove;
   getExecutionSession().runSessionLocked([&] {
     auto I = Allocs.find(K);
     if (I != Allocs.end()) {
@@ -708,12 +710,7 @@ Error ObjectLinkingLayer::handleRemoveResources(ResourceKey K) {
     }
   });
 
-  while (!AllocsToRemove.empty()) {
-    Err = joinErrors(std::move(Err), AllocsToRemove.back()->deallocate());
-    AllocsToRemove.pop_back();
-  }
-
-  return Err;
+  return MemMgr.deallocate(std::move(AllocsToRemove));
 }
 
 void ObjectLinkingLayer::handleTransferResources(ResourceKey DstKey,
diff --git a/llvm/lib/ExecutionEngine/Orc/TargetProcess/JITLoaderGDB.cpp b/llvm/lib/ExecutionEngine/Orc/TargetProcess/JITLoaderGDB.cpp
index 0ee194c4cc879c..787a6c6b4c1624 100644
--- a/llvm/lib/ExecutionEngine/Orc/TargetProcess/JITLoaderGDB.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/TargetProcess/JITLoaderGDB.cpp
@@ -64,15 +64,16 @@ LLVM_ATTRIBUTE_NOINLINE void __jit_debug_register_code() {
 }
 
 using namespace llvm;
+using namespace llvm::orc;
 
 // Serialize rendezvous with the debugger as well as access to shared data.
 ManagedStatic<std::mutex> JITDebugLock;
 
 // Register debug object, return error message or null for success.
-static void registerJITLoaderGDBImpl(JITTargetAddress Addr, uint64_t Size) {
+static void registerJITLoaderGDBImpl(ExecutorAddrRange DebugObjRange) {
   jit_code_entry *E = new jit_code_entry;
-  E->symfile_addr = jitTargetAddressToPointer<const char *>(Addr);
-  E->symfile_size = Size;
+  E->symfile_addr = DebugObjRange.Start.toPtr<const char *>();
+  E->symfile_size = DebugObjRange.size().getValue();
   E->prev_entry = nullptr;
 
   std::lock_guard<std::mutex> Lock(*JITDebugLock);
@@ -95,7 +96,7 @@ static void registerJITLoaderGDBImpl(JITTargetAddress Addr, uint64_t Size) {
 extern "C" orc::shared::detail::CWrapperFunctionResult
 llvm_orc_registerJITLoaderGDBWrapper(const char *Data, uint64_t Size) {
   using namespace orc::shared;
-  return WrapperFunction<void(SPSExecutorAddr, uint64_t)>::handle(
+  return WrapperFunction<void(SPSExecutorAddrRange)>::handle(
              Data, Size, registerJITLoaderGDBImpl)
       .release();
 }
diff --git a/llvm/tools/llvm-jitlink/llvm-jitlink.cpp b/llvm/tools/llvm-jitlink/llvm-jitlink.cpp
index 50ce6e870cea98..3b9972fe49a8cf 100644
--- a/llvm/tools/llvm-jitlink/llvm-jitlink.cpp
+++ b/llvm/tools/llvm-jitlink/llvm-jitlink.cpp
@@ -357,6 +357,12 @@ static void dumpSectionContents(raw_ostream &OS, LinkGraph &G) {
 }
 
 class JITLinkSlabAllocator final : public JITLinkMemoryManager {
+private:
+  struct FinalizedAllocInfo {
+    sys::MemoryBlock Mem;
+    std::vector<AllocActionCall> DeallocActions;
+  };
+
 public:
   static Expected<std::unique_ptr<JITLinkSlabAllocator>>
   Create(uint64_t SlabSize) {
@@ -368,101 +374,161 @@ class JITLinkSlabAllocator final : public JITLinkMemoryManager {
     return std::move(Allocator);
   }
 
-  Expected<std::unique_ptr<JITLinkMemoryManager::Allocation>>
-  allocate(const JITLinkDylib *JD, const SegmentsRequestMap &Request) override {
-
-    using AllocationMap = DenseMap<unsigned, sys::MemoryBlock>;
+  void allocate(const JITLinkDylib *JD, LinkGraph &G,
+                OnAllocatedFunction OnAllocated) override {
 
     // Local class for allocation.
-    class IPMMAlloc : public Allocation {
+    class IPMMAlloc : public InFlightAlloc {
     public:
-      IPMMAlloc(JITLinkSlabAllocator &Parent, AllocationMap SegBlocks)
-          : Parent(Parent), SegBlocks(std::move(SegBlocks)) {}
-      MutableArrayRef<char> getWorkingMemory(ProtectionFlags Seg) override {
-        assert(SegBlocks.count(Seg) && "No allocation for segment");
-        return {static_cast<char *>(SegBlocks[Seg].base()),
-                SegBlocks[Seg].allocatedSize()};
-      }
-      JITTargetAddress getTargetMemory(ProtectionFlags Seg) override {
-        assert(SegBlocks.count(Seg) && "No allocation for segment");
-        return pointerToJITTargetAddress(SegBlocks[Seg].base()) +
-               Parent.TargetDelta;
-      }
-      void finalizeAsync(FinalizeContinuation OnFinalize) override {
-        OnFinalize(applyProtections());
+      IPMMAlloc(JITLinkSlabAllocator &Parent, BasicLayout BL,
+                sys::MemoryBlock StandardSegs, sys::MemoryBlock FinalizeSegs)
+          : Parent(Parent), BL(std::move(BL)),
+            StandardSegs(std::move(StandardSegs)),
+            FinalizeSegs(std::move(FinalizeSegs)) {}
+
+      void finalize(OnFinalizedFunction OnFinalized) override {
+        if (auto Err = applyProtections()) {
+          OnFinalized(std::move(Err));
+          return;
+        }
+
+        // FIXME: Run finalize actions.
+        assert(BL.graphAllocActions().empty() &&
+               "Support function calls not supported yet");
+
+        OnFinalized(FinalizedAlloc(
+            pointerToJITTargetAddress(new FinalizedAllocInfo())));
       }
-      Error deallocate() override {
-        for (auto &KV : SegBlocks)
-          if (auto EC = sys::Memory::releaseMappedMemory(KV.second))
-            return errorCodeToError(EC);
-        return Error::success();
+
+      void abandon(OnAbandonedFunction OnAbandoned) override {
+        OnAbandoned(joinErrors(Parent.freeBlock(StandardSegs),
+                               Parent.freeBlock(FinalizeSegs)));
       }
 
     private:
       Error applyProtections() {
-        for (auto &KV : SegBlocks) {
-          auto &Prot = KV.first;
-          auto &Block = KV.second;
-          if (auto EC = sys::Memory::protectMappedMemory(Block, Prot))
+        for (auto &KV : BL.segments()) {
+          const auto &Group = KV.first;
+          auto &Seg = KV.second;
+
+          auto Prot = toSysMemoryProtectionFlags(Group.getMemProt());
+
+          uint64_t SegSize =
+              alignTo(Seg.ContentSize + Seg.ZeroFillSize, Parent.PageSize);
+          sys::MemoryBlock MB(Seg.WorkingMem, SegSize);
+          if (auto EC = sys::Memory::protectMappedMemory(MB, Prot))
             return errorCodeToError(EC);
           if (Prot & sys::Memory::MF_EXEC)
-            sys::Memory::InvalidateInstructionCache(Block.base(),
-                                                    Block.allocatedSize());
+            sys::Memory::InvalidateInstructionCache(MB.base(),
+                                                    MB.allocatedSize());
         }
         return Error::success();
       }
 
       JITLinkSlabAllocator &Parent;
-      AllocationMap SegBlocks;
+      BasicLayout BL;
+      sys::MemoryBlock StandardSegs;
+      sys::MemoryBlock FinalizeSegs;
     };
 
-    AllocationMap Blocks;
+    BasicLayout BL(G);
+    auto SegsSizes = BL.getContiguousPageBasedLayoutSizes(PageSize);
 
-    for (auto &KV : Request) {
-      auto &Seg = KV.second;
+    if (!SegsSizes) {
+      OnAllocated(SegsSizes.takeError());
+      return;
+    }
 
-      if (Seg.getAlignment() > PageSize)
-        return make_error<StringError>("Cannot request higher than page "
-                                       "alignment",
-                                       inconvertibleErrorCode());
+    char *AllocBase = 0;
+    {
+      std::lock_guard<std::mutex> Lock(SlabMutex);
 
-      if (PageSize % Seg.getAlignment() != 0)
-        return make_error<StringError>("Page size is not a multiple of "
-                                       "alignment",
-                                       inconvertibleErrorCode());
+      if (SegsSizes->total() > SlabRemaining.allocatedSize()) {
+        OnAllocated(make_error<StringError>(
+            "Slab allocator out of memory: request for " +
+                formatv("{0:x}", SegsSizes->total()) +
+                " bytes exceeds remaining capacity of " +
+                formatv("{0:x}", SlabRemaining.allocatedSize()) + " bytes",
+            inconvertibleErrorCode()));
+        return;
+      }
 
-      uint64_t ZeroFillStart = Seg.getContentSize();
-      uint64_t SegmentSize = ZeroFillStart + Seg.getZeroFillSize();
+      AllocBase = reinterpret_cast<char *>(SlabRemaining.base());
+      SlabRemaining =
+          sys::MemoryBlock(AllocBase + SegsSizes->total(),
+                           SlabRemaining.allocatedSize() - SegsSizes->total());
+    }
 
-      // Round segment size up to page boundary.
-      SegmentSize = (SegmentSize + PageSize - 1) & ~(PageSize - 1);
+    sys::MemoryBlock StandardSegs(AllocBase, SegsSizes->StandardSegs);
+    sys::MemoryBlock FinalizeSegs(AllocBase + SegsSizes->StandardSegs,
+                                  SegsSizes->FinalizeSegs);
+
+    auto NextStandardSegAddr = pointerToJITTargetAddress(StandardSegs.base());
+    auto NextFinalizeSegAddr = pointerToJITTargetAddress(FinalizeSegs.base());
+
+    LLVM_DEBUG({
+      dbgs() << "JITLinkSlabAllocator allocated:\n";
+      if (SegsSizes->StandardSegs)
+        dbgs() << formatv("  [ {0:x16} -- {1:x16} ]", NextStandardSegAddr,
+                          NextStandardSegAddr + StandardSegs.allocatedSize())
+               << " to stardard segs\n";
+      else
+        dbgs() << "  no standard segs\n";
+      if (SegsSizes->FinalizeSegs)
+        dbgs() << formatv("  [ {0:x16} -- {1:x16} ]", NextFinalizeSegAddr,
+                          NextFinalizeSegAddr + FinalizeSegs.allocatedSize())
+               << " to finalize segs\n";
+      else
+        dbgs() << "  no finalize segs\n";
+    });
 
-      // Take segment bytes from the front of the slab.
-      void *SlabBase = SlabRemaining.base();
-      uint64_t SlabRemainingSize = SlabRemaining.allocatedSize();
+    for (auto &KV : BL.segments()) {
+      auto &Group = KV.first;
+      auto &Seg = KV.second;
 
-      if (SegmentSize > SlabRemainingSize)
-        return make_error<StringError>(
-            "Slab allocator out of memory: request for " +
-                formatv("{0:x}", SegmentSize) +
-                " bytes exceeds remaining capacity of " +
-                formatv("{0:x}", SlabRemainingSize) + " bytes",
-            inconvertibleErrorCode());
+      auto &SegAddr =
+          (Group.getMemDeallocPolicy() == MemDeallocPolicy::Standard)
+              ? NextStandardSegAddr
+              : NextFinalizeSegAddr;
 
-      sys::MemoryBlock SegMem(SlabBase, SegmentSize);
-      SlabRemaining =
-          sys::MemoryBlock(reinterpret_cast<char *>(SlabBase) + SegmentSize,
-                           SlabRemainingSize - SegmentSize);
+      LLVM_DEBUG({
+        dbgs() << "  " << Group << " -> " << formatv("{0:x16}", SegAddr)
+               << "\n";
+      });
+      Seg.WorkingMem = jitTargetAddressToPointer<char *>(SegAddr);
+      Seg.Addr = SegAddr + NextSlabDelta;
+
+      SegAddr += alignTo(Seg.ContentSize + Seg.ZeroFillSize, PageSize);
 
       // Zero out the zero-fill memory.
-      memset(static_cast<char *>(SegMem.base()) + ZeroFillStart, 0,
-             Seg.getZeroFillSize());
+      if (Seg.ZeroFillSize != 0)
+        memset(Seg.WorkingMem + Seg.ContentSize, 0, Seg.ZeroFillSize);
+    }
 
-      // Record the block for this segment.
-      Blocks[KV.first] = std::move(SegMem);
+    NextSlabDelta += SegsSizes->total();
+
+    if (auto Err = BL.apply()) {
+      OnAllocated(std::move(Err));
+      return;
     }
-    return std::unique_ptr<InProcessMemoryManager::Allocation>(
-        new IPMMAlloc(*this, std::move(Blocks)));
+
+    OnAllocated(std::unique_ptr<InProcessMemoryManager::InFlightAlloc>(
+        new IPMMAlloc(*this, std::move(BL), std::move(StandardSegs),
+                      std::move(FinalizeSegs))));
+  }
+
+  void deallocate(std::vector<FinalizedAlloc> FinalizedAllocs,
+                  OnDeallocatedFunction OnDeallocated) override {
+    Error Err = Error::success();
+    for (auto &FA : FinalizedAllocs) {
+      std::unique_ptr<FinalizedAllocInfo> FAI(
+          jitTargetAddressToPointer<FinalizedAllocInfo *>(FA.release()));
+
+      // FIXME: Run dealloc actions.
+
+      Err = joinErrors(std::move(Err), freeBlock(FAI->Mem));
+    }
+    OnDeallocated(std::move(Err));
   }
 
 private:
@@ -510,13 +576,19 @@ class JITLinkSlabAllocator final : public JITLinkMemoryManager {
     // Calculate the target address delta to link as-if slab were at
     // SlabAddress.
     if (SlabAddress != ~0ULL)
-      TargetDelta =
+      NextSlabDelta =
           SlabAddress - pointerToJITTargetAddress(SlabRemaining.base());
   }
 
+  Error freeBlock(sys::MemoryBlock MB) {
+    // FIXME: Return memory to slab.
+    return Error::success();
+  }
+
+  std::mutex SlabMutex;
   sys::MemoryBlock SlabRemaining;
   uint64_t PageSize = 0;
-  int64_t TargetDelta = 0;
+  int64_t NextSlabDelta = 0;
 };
 
 Expected<uint64_t> getSlabAllocSize(StringRef SizeString) {
@@ -547,7 +619,7 @@ static std::unique_ptr<JITLinkMemoryManager> createMemoryManager() {
     auto SlabSize = ExitOnErr(getSlabAllocSize(SlabAllocateSizeString));
     return ExitOnErr(JITLinkSlabAllocator::Create(SlabSize));
   }
-  return std::make_unique<InProcessMemoryManager>();
+  return ExitOnErr(InProcessMemoryManager::Create());
 }
 
 LLVMJITLinkObjectLinkingLayer::LLVMJITLinkObjectLinkingLayer(
diff --git a/llvm/unittests/ExecutionEngine/JITLink/LinkGraphTests.cpp b/llvm/unittests/ExecutionEngine/JITLink/LinkGraphTests.cpp
index b15a96c3e09674..964bef5991780c 100644
--- a/llvm/unittests/ExecutionEngine/JITLink/LinkGraphTests.cpp
+++ b/llvm/unittests/ExecutionEngine/JITLink/LinkGraphTests.cpp
@@ -15,9 +15,6 @@
 using namespace llvm;
 using namespace llvm::jitlink;
 
-static auto RWFlags =
-    sys::Memory::ProtectionFlags(sys::Memory::MF_READ | sys::Memory::MF_WRITE);
-
 static const char BlockContentBytes[] = {
     0x54, 0x68, 0x65, 0x72, 0x65, 0x20, 0x77, 0x61, 0x73, 0x20, 0x6d, 0x6f,
     0x76, 0x65, 0x6d, 0x65, 0x6e, 0x74, 0x20, 0x61, 0x74, 0x20, 0x74, 0x68,
@@ -78,7 +75,7 @@ TEST(LinkGraphTest, AddressAccess) {
   LinkGraph G("foo", Triple("x86_64-apple-darwin"), 8, support::little,
               getGenericEdgeKindName);
 
-  auto &Sec1 = G.createSection("__data.1", RWFlags);
+  auto &Sec1 = G.createSection("__data.1", MemProt::Read | MemProt::Write);
   auto &B1 = G.createContentBlock(Sec1, BlockContent, 0x1000, 8, 0);
   auto &S1 = G.addDefinedSymbol(B1, 4, "S1", 4, Linkage::Strong, Scope::Default,
                                 false, false);
@@ -94,7 +91,7 @@ TEST(LinkGraphTest, BlockAndSymbolIteration) {
   // Check that we can iterate over blocks within Sections and across sections.
   LinkGraph G("foo", Triple("x86_64-apple-darwin"), 8, support::little,
               getGenericEdgeKindName);
-  auto &Sec1 = G.createSection("__data.1", RWFlags);
+  auto &Sec1 = G.createSection("__data.1", MemProt::Read | MemProt::Write);
   auto &B1 = G.createContentBlock(Sec1, BlockContent, 0x1000, 8, 0);
   auto &B2 = G.createContentBlock(Sec1, BlockContent, 0x2000, 8, 0);
   auto &S1 = G.addDefinedSymbol(B1, 0, "S1", 4, Linkage::Strong, Scope::Default,
@@ -102,7 +99,7 @@ TEST(LinkGraphTest, BlockAndSymbolIteration) {
   auto &S2 = G.addDefinedSymbol(B2, 4, "S2", 4, Linkage::Strong, Scope::Default,
                                 false, false);
 
-  auto &Sec2 = G.createSection("__data.2", RWFlags);
+  auto &Sec2 = G.createSection("__data.2", MemProt::Read | MemProt::Write);
   auto &B3 = G.createContentBlock(Sec2, BlockContent, 0x3000, 8, 0);
   auto &B4 = G.createContentBlock(Sec2, BlockContent, 0x4000, 8, 0);
   auto &S3 = G.addDefinedSymbol(B3, 0, "S3", 4, Linkage::Strong, Scope::Default,
@@ -141,7 +138,7 @@ TEST(LinkGraphTest, ContentAccessAndUpdate) {
   // Check that we can make a defined symbol external.
   LinkGraph G("foo", Triple("x86_64-apple-darwin"), 8, support::little,
               getGenericEdgeKindName);
-  auto &Sec = G.createSection("__data", RWFlags);
+  auto &Sec = G.createSection("__data", MemProt::Read | MemProt::Write);
 
   // Create an initial block.
   auto &B = G.createContentBlock(Sec, BlockContent, 0x1000, 8, 0);
@@ -208,7 +205,7 @@ TEST(LinkGraphTest, MakeExternal) {
   // Check that we can make a defined symbol external.
   LinkGraph G("foo", Triple("x86_64-apple-darwin"), 8, support::little,
               getGenericEdgeKindName);
-  auto &Sec = G.createSection("__data", RWFlags);
+  auto &Sec = G.createSection("__data", MemProt::Read | MemProt::Write);
 
   // Create an initial block.
   auto &B1 = G.createContentBlock(Sec, BlockContent, 0x1000, 8, 0);
@@ -253,7 +250,7 @@ TEST(LinkGraphTest, MakeDefined) {
   // Check that we can make an external symbol defined.
   LinkGraph G("foo", Triple("x86_64-apple-darwin"), 8, support::little,
               getGenericEdgeKindName);
-  auto &Sec = G.createSection("__data", RWFlags);
+  auto &Sec = G.createSection("__data", MemProt::Read | MemProt::Write);
 
   // Create an initial block.
   auto &B1 = G.createContentBlock(Sec, BlockContent, 0x1000, 8, 0);
@@ -297,7 +294,7 @@ TEST(LinkGraphTest, TransferDefinedSymbol) {
   // Check that we can transfer a defined symbol from one block to another.
   LinkGraph G("foo", Triple("x86_64-apple-darwin"), 8, support::little,
               getGenericEdgeKindName);
-  auto &Sec = G.createSection("__data", RWFlags);
+  auto &Sec = G.createSection("__data", MemProt::Read | MemProt::Write);
 
   // Create an initial block.
   auto &B1 = G.createContentBlock(Sec, BlockContent, 0x1000, 8, 0);
@@ -328,8 +325,8 @@ TEST(LinkGraphTest, TransferDefinedSymbolAcrossSections) {
   // section to another.
   LinkGraph G("foo", Triple("x86_64-apple-darwin"), 8, support::little,
               getGenericEdgeKindName);
-  auto &Sec1 = G.createSection("__data.1", RWFlags);
-  auto &Sec2 = G.createSection("__data.2", RWFlags);
+  auto &Sec1 = G.createSection("__data.1", MemProt::Read | MemProt::Write);
+  auto &Sec2 = G.createSection("__data.2", MemProt::Read | MemProt::Write);
 
   // Create blocks in each section.
   auto &B1 = G.createContentBlock(Sec1, BlockContent, 0x1000, 8, 0);
@@ -357,8 +354,8 @@ TEST(LinkGraphTest, TransferBlock) {
   // section to another.
   LinkGraph G("foo", Triple("x86_64-apple-darwin"), 8, support::little,
               getGenericEdgeKindName);
-  auto &Sec1 = G.createSection("__data.1", RWFlags);
-  auto &Sec2 = G.createSection("__data.2", RWFlags);
+  auto &Sec1 = G.createSection("__data.1", MemProt::Read | MemProt::Write);
+  auto &Sec2 = G.createSection("__data.2", MemProt::Read | MemProt::Write);
 
   // Create an initial block.
   auto &B1 = G.createContentBlock(Sec1, BlockContent, 0x1000, 8, 0);
@@ -401,9 +398,9 @@ TEST(LinkGraphTest, MergeSections) {
   // section to another.
   LinkGraph G("foo", Triple("x86_64-apple-darwin"), 8, support::little,
               getGenericEdgeKindName);
-  auto &Sec1 = G.createSection("__data.1", RWFlags);
-  auto &Sec2 = G.createSection("__data.2", RWFlags);
-  auto &Sec3 = G.createSection("__data.3", RWFlags);
+  auto &Sec1 = G.createSection("__data.1", MemProt::Read | MemProt::Write);
+  auto &Sec2 = G.createSection("__data.2", MemProt::Read | MemProt::Write);
+  auto &Sec3 = G.createSection("__data.3", MemProt::Read | MemProt::Write);
 
   // Create an initial block.
   auto &B1 = G.createContentBlock(Sec1, BlockContent, 0x1000, 8, 0);
@@ -475,7 +472,7 @@ TEST(LinkGraphTest, SplitBlock) {
   // Check that the LinkGraph::splitBlock test works as expected.
   LinkGraph G("foo", Triple("x86_64-apple-darwin"), 8, support::little,
               getGenericEdgeKindName);
-  auto &Sec = G.createSection("__data", RWFlags);
+  auto &Sec = G.createSection("__data", MemProt::Read | MemProt::Write);
 
   // Create the block to split.
   auto &B1 = G.createContentBlock(Sec, BlockContent, 0x1000, 8, 0);
diff --git a/llvm/unittests/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManagerTest.cpp b/llvm/unittests/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManagerTest.cpp
index f6ec09d5bfdff7..e7e4e561b56098 100644
--- a/llvm/unittests/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManagerTest.cpp
+++ b/llvm/unittests/ExecutionEngine/Orc/EPCGenericJITLinkMemoryManagerTest.cpp
@@ -116,27 +116,24 @@ TEST(EPCGenericJITLinkMemoryManagerTest, AllocFinalizeFree) {
 
   auto MemMgr = std::make_unique<EPCGenericJITLinkMemoryManager>(*SelfEPC, SAs);
 
-  jitlink::JITLinkMemoryManager::SegmentsRequestMap SRM;
   StringRef Hello = "hello";
-  SRM[sys::Memory::MF_READ] = {8, Hello.size(), 8};
-  auto Alloc = MemMgr->allocate(nullptr, SRM);
-  EXPECT_THAT_EXPECTED(Alloc, Succeeded());
+  auto SSA = jitlink::SimpleSegmentAlloc::Create(
+      *MemMgr, nullptr, {{jitlink::MemProt::Read, {Hello.size(), Align(1)}}});
+  EXPECT_THAT_EXPECTED(SSA, Succeeded());
+  auto SegInfo = SSA->getSegInfo(jitlink::MemProt::Read);
+  memcpy(SegInfo.WorkingMem.data(), Hello.data(), Hello.size());
 
-  MutableArrayRef<char> WorkingMem =
-      (*Alloc)->getWorkingMemory(sys::Memory::MF_READ);
-  memcpy(WorkingMem.data(), Hello.data(), Hello.size());
+  auto FA = SSA->finalize();
+  EXPECT_THAT_EXPECTED(FA, Succeeded());
 
-  auto Err = (*Alloc)->finalize();
-  EXPECT_THAT_ERROR(std::move(Err), Succeeded());
-
-  ExecutorAddr TargetAddr((*Alloc)->getTargetMemory(sys::Memory::MF_READ));
+  ExecutorAddr TargetAddr(SegInfo.Addr);
 
   const char *TargetMem = TargetAddr.toPtr<const char *>();
-  EXPECT_NE(TargetMem, WorkingMem.data());
+  EXPECT_NE(TargetMem, SegInfo.WorkingMem.data());
   StringRef TargetHello(TargetMem, Hello.size());
   EXPECT_EQ(Hello, TargetHello);
 
-  auto Err2 = (*Alloc)->deallocate();
+  auto Err2 = MemMgr->deallocate(std::move(*FA));
   EXPECT_THAT_ERROR(std::move(Err2), Succeeded());
 }
 
diff --git a/llvm/unittests/ExecutionEngine/Orc/ObjectLinkingLayerTest.cpp b/llvm/unittests/ExecutionEngine/Orc/ObjectLinkingLayerTest.cpp
index f6413316b692df..0181c558b60d09 100644
--- a/llvm/unittests/ExecutionEngine/Orc/ObjectLinkingLayerTest.cpp
+++ b/llvm/unittests/ExecutionEngine/Orc/ObjectLinkingLayerTest.cpp
@@ -19,9 +19,6 @@ using namespace llvm::orc;
 
 namespace {
 
-auto RWFlags =
-    sys::Memory::ProtectionFlags(sys::Memory::MF_READ | sys::Memory::MF_WRITE);
-
 const char BlockContentBytes[] = {0x01, 0x02, 0x03, 0x04,
                                   0x05, 0x06, 0x07, 0x08};
 
@@ -38,7 +35,7 @@ class ObjectLinkingLayerTest : public testing::Test {
   ExecutionSession ES{std::make_unique<UnsupportedExecutorProcessControl>()};
   JITDylib &JD = ES.createBareJITDylib("main");
   ObjectLinkingLayer ObjLinkingLayer{
-      ES, std::make_unique<InProcessMemoryManager>()};
+      ES, std::make_unique<InProcessMemoryManager>(4096)};
 };
 
 TEST_F(ObjectLinkingLayerTest, AddLinkGraph) {
@@ -46,7 +43,7 @@ TEST_F(ObjectLinkingLayerTest, AddLinkGraph) {
       std::make_unique<LinkGraph>("foo", Triple("x86_64-apple-darwin"), 8,
                                   support::little, x86_64::getEdgeKindName);
 
-  auto &Sec1 = G->createSection("__data", RWFlags);
+  auto &Sec1 = G->createSection("__data", MemProt::Read | MemProt::Write);
   auto &B1 = G->createContentBlock(Sec1, BlockContent, 0x1000, 8, 0);
   G->addDefinedSymbol(B1, 4, "_X", 4, Linkage::Strong, Scope::Default, false,
                       false);