diff --git a/llvm/include/llvm/IR/AutoUpgrade.h b/llvm/include/llvm/IR/AutoUpgrade.h
--- a/llvm/include/llvm/IR/AutoUpgrade.h
+++ b/llvm/include/llvm/IR/AutoUpgrade.h
@@ -87,6 +87,10 @@
   /// Upgrade the loop attachment metadata node.
   MDNode *upgradeInstructionLoopAttachment(MDNode &N);
 
+  /// Upgrade the datalayout string by adding a section for address space
+  /// pointers.
+  StringRef UpgradeDataLayoutString(StringRef DL, StringRef Triple);
+
 } // End llvm namespace
 
 #endif
diff --git a/llvm/include/llvm/Target/TargetMachine.h b/llvm/include/llvm/Target/TargetMachine.h
--- a/llvm/include/llvm/Target/TargetMachine.h
+++ b/llvm/include/llvm/Target/TargetMachine.h
@@ -157,7 +157,7 @@
   /// The LLVM Module owns a DataLayout that is used for the target independent
   /// optimizations and code generation. This hook provides a target specific
   /// check on the validity of this DataLayout.
-  virtual bool isCompatibleDataLayout(const DataLayout &Candidate) const {
+  bool isCompatibleDataLayout(const DataLayout &Candidate) const {
     return DL == Candidate;
   }
 
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -3649,6 +3649,11 @@
     }
     Record.clear();
   }
+
+  // Upgrade data layout string.
+  StringRef DL = llvm::UpgradeDataLayoutString(TheModule->getDataLayoutStr(),
+                                               TheModule->getTargetTriple());
+  TheModule->setDataLayout(DL);
 }
 
 Error BitcodeReader::parseBitcodeInto(Module *M, bool ShouldLazyLoadMetadata,
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -4113,3 +4113,23 @@
 
   return MDTuple::get(T->getContext(), Ops);
 }
+
+StringRef llvm::UpgradeDataLayoutString(StringRef DL, StringRef TT) {
+  std::string AddrSpaces = "-p270:32:32-p271:32:32-p272:64:64";
+
+  // If X86, and the datalayout matches the expected format, add pointer size
+  // address spaces to the datalayout.
+  Triple::ArchType Arch = Triple(TT).getArch();
+  if ((Arch != llvm::Triple::x86 && Arch != llvm::Triple::x86_64) ||
+      DL.contains(AddrSpaces))
+    return DL;
+
+  SmallVector<StringRef, 4> Groups;
+  Regex R("(e-m:[a-z](-p:32:32)?)(-[if]64:.*$)");
+  if (!R.match(DL, &Groups))
+    return DL;
+
+  SmallString<1024> Buf;
+  StringRef Res = (Groups[1] + AddrSpaces + Groups[3]).toStringRef(Buf);
+  return Res;
+}
diff --git a/llvm/lib/Target/X86/X86TargetMachine.h b/llvm/lib/Target/X86/X86TargetMachine.h
--- a/llvm/lib/Target/X86/X86TargetMachine.h
+++ b/llvm/lib/Target/X86/X86TargetMachine.h
@@ -30,7 +30,6 @@
 class X86TargetMachine final : public LLVMTargetMachine {
   std::unique_ptr<TargetLoweringObjectFile> TLOF;
   mutable StringMap<std::unique_ptr<X86Subtarget>> SubtargetMap;
-  const DataLayout DLNoAddrSpaces;
 
 public:
   X86TargetMachine(const Target &T, const Triple &TT, StringRef CPU,
@@ -53,8 +52,6 @@
   TargetLoweringObjectFile *getObjFileLowering() const override {
     return TLOF.get();
   }
-
-  bool isCompatibleDataLayout(const DataLayout &Candidate) const override;
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/Target/X86/X86TargetMachine.cpp b/llvm/lib/Target/X86/X86TargetMachine.cpp
--- a/llvm/lib/Target/X86/X86TargetMachine.cpp
+++ b/llvm/lib/Target/X86/X86TargetMachine.cpp
@@ -106,8 +106,7 @@
   llvm_unreachable("unknown subtarget type");
 }
 
-static std::string computeDataLayout(const Triple &TT,
-                                     bool AddressSpaces = true) {
+static std::string computeDataLayout(const Triple &TT) {
   // X86 is little endian
   std::string Ret = "e";
 
@@ -119,8 +118,7 @@
     Ret += "-p:32:32";
 
   // Address spaces for 32 bit signed, 32 bit unsigned, and 64 bit pointers.
-  if (AddressSpaces)
-    Ret += "-p270:32:32-p271:32:32-p272:64:64";
+  Ret += "-p270:32:32-p271:32:32-p272:64:64";
 
   // Some ABIs align 64 bit integers and doubles to 64 bits, others to 32.
   if (TT.isArch64Bit() || TT.isOSWindows() || TT.isOSNaCl())
@@ -223,8 +221,7 @@
           getEffectiveRelocModel(TT, JIT, RM),
           getEffectiveX86CodeModel(CM, JIT, TT.getArch() == Triple::x86_64),
           OL),
-      TLOF(createTLOF(getTargetTriple())),
-      DLNoAddrSpaces(computeDataLayout(TT, /*AddressSpaces=*/false)) {
+      TLOF(createTLOF(getTargetTriple())) {
   // On PS4, the "return address" of a 'noreturn' call must still be within
   // the calling function, and TrapUnreachable is an easy way to get that.
   if (TT.isPS4() || TT.isOSBinFormatMachO()) {
@@ -318,13 +315,6 @@
   return I.get();
 }
 
-bool X86TargetMachine::isCompatibleDataLayout(
-    const DataLayout &Candidate) const {
-  // Maintain compatibility with datalayouts that don't have address space
-  // pointer sizes.
-  return DL == Candidate || DLNoAddrSpaces == Candidate;
-}
-
 //===----------------------------------------------------------------------===//
 // Command line options for x86
 //===----------------------------------------------------------------------===//
diff --git a/llvm/test/Bitcode/upgrade-datalayout.ll b/llvm/test/Bitcode/upgrade-datalayout.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Bitcode/upgrade-datalayout.ll
@@ -0,0 +1,9 @@
+; Test to make sure datalayout is automatically upgraded.
+;
+; RUN: llvm-as %s -o - | llvm-dis - | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK: target datalayout = "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
diff --git a/llvm/test/Bitcode/upgrade-datalayout2.ll b/llvm/test/Bitcode/upgrade-datalayout2.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Bitcode/upgrade-datalayout2.ll
@@ -0,0 +1,10 @@
+; Test to make sure datalayout is not automatically upgraded if it does not
+; match a possible x86 datalayout.
+;
+; RUN: llvm-as %s -o - | llvm-dis - | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK: target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
diff --git a/llvm/test/Bitcode/upgrade-datalayout3.ll b/llvm/test/Bitcode/upgrade-datalayout3.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Bitcode/upgrade-datalayout3.ll
@@ -0,0 +1,8 @@
+; Test to make sure datalayout is automatically upgraded.
+;
+; RUN: llvm-as %s -o - | llvm-dis - | FileCheck %s
+
+target datalayout = "e-m:w-p:32:32-i64:64-f80:32-n8:16:32-S32"
+target triple = "i686-pc-windows-msvc"
+
+; CHECK: target datalayout = "e-m:w-p:32:32-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:32-n8:16:32-S32"