diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -2370,6 +2370,14 @@
     program memory space defaults to the default address space of 0,
     which corresponds to a Von Neumann architecture that has code
     and data in the same space.
+``G<address space>``
+    Specifies the address space to be used by default when creating global
+    variables. If omitted, the globals address space defaults to the default
+    address space 0.
+    Note: variable declarations without an address space are always created in
+    address space 0, this property only affects the default value to be used
+    when creating globals without additional contextual information (e.g. in
+    LLVM passes).
 ``A<address space>``
     Specifies the address space of objects created by '``alloca``'.
     Defaults to the default address space of 0.
diff --git a/llvm/include/llvm/IR/DataLayout.h b/llvm/include/llvm/IR/DataLayout.h
--- a/llvm/include/llvm/IR/DataLayout.h
+++ b/llvm/include/llvm/IR/DataLayout.h
@@ -123,6 +123,7 @@
   unsigned AllocaAddrSpace;
   MaybeAlign StackNaturalAlign;
   unsigned ProgramAddrSpace;
+  unsigned DefaultGlobalsAddrSpace;
 
   MaybeAlign FunctionPtrAlign;
   FunctionPtrAlignType TheFunctionPtrAlignType;
@@ -219,6 +220,7 @@
     FunctionPtrAlign = DL.FunctionPtrAlign;
     TheFunctionPtrAlignType = DL.TheFunctionPtrAlignType;
     ProgramAddrSpace = DL.ProgramAddrSpace;
+    DefaultGlobalsAddrSpace = DL.DefaultGlobalsAddrSpace;
     ManglingMode = DL.ManglingMode;
     LegalIntWidths = DL.LegalIntWidths;
     Alignments = DL.Alignments;
@@ -295,6 +297,9 @@
   }
 
   unsigned getProgramAddressSpace() const { return ProgramAddrSpace; }
+  unsigned getDefaultGlobalsAddressSpace() const {
+    return DefaultGlobalsAddrSpace;
+  }
 
   bool hasMicrosoftFastStdCallMangling() const {
     return ManglingMode == MM_WinCOFFX86;
diff --git a/llvm/include/llvm/IR/GlobalVariable.h b/llvm/include/llvm/IR/GlobalVariable.h
--- a/llvm/include/llvm/IR/GlobalVariable.h
+++ b/llvm/include/llvm/IR/GlobalVariable.h
@@ -56,10 +56,11 @@
                  bool isExternallyInitialized = false);
   /// GlobalVariable ctor - This creates a global and inserts it before the
   /// specified other global.
-  GlobalVariable(Module &M, Type *Ty, bool isConstant,
-                 LinkageTypes Linkage, Constant *Initializer,
-                 const Twine &Name = "", GlobalVariable *InsertBefore = nullptr,
-                 ThreadLocalMode = NotThreadLocal, unsigned AddressSpace = 0,
+  GlobalVariable(Module &M, Type *Ty, bool isConstant, LinkageTypes Linkage,
+                 Constant *Initializer, const Twine &Name = "",
+                 GlobalVariable *InsertBefore = nullptr,
+                 ThreadLocalMode = NotThreadLocal,
+                 Optional<unsigned> AddressSpace = None,
                  bool isExternallyInitialized = false);
   GlobalVariable(const GlobalVariable &) = delete;
   GlobalVariable &operator=(const GlobalVariable &) = delete;
diff --git a/llvm/lib/IR/DataLayout.cpp b/llvm/lib/IR/DataLayout.cpp
--- a/llvm/lib/IR/DataLayout.cpp
+++ b/llvm/lib/IR/DataLayout.cpp
@@ -182,6 +182,7 @@
   AllocaAddrSpace = 0;
   StackNaturalAlign.reset();
   ProgramAddrSpace = 0;
+  DefaultGlobalsAddrSpace = 0;
   FunctionPtrAlign.reset();
   TheFunctionPtrAlignType = FunctionPtrAlignType::Independent;
   ManglingMode = MM_None;
@@ -479,6 +480,11 @@
         return Err;
       break;
     }
+    case 'G': { // Default address space for global variables.
+      if (Error Err = getAddrSpace(Tok, DefaultGlobalsAddrSpace))
+        return Err;
+      break;
+    }
     case 'm':
       if (!Tok.empty())
         return reportError("Unexpected trailing characters after mangling "
@@ -530,6 +536,7 @@
              AllocaAddrSpace == Other.AllocaAddrSpace &&
              StackNaturalAlign == Other.StackNaturalAlign &&
              ProgramAddrSpace == Other.ProgramAddrSpace &&
+             DefaultGlobalsAddrSpace == Other.DefaultGlobalsAddrSpace &&
              FunctionPtrAlign == Other.FunctionPtrAlign &&
              TheFunctionPtrAlignType == Other.TheFunctionPtrAlignType &&
              ManglingMode == Other.ManglingMode &&
diff --git a/llvm/lib/IR/Globals.cpp b/llvm/lib/IR/Globals.cpp
--- a/llvm/lib/IR/Globals.cpp
+++ b/llvm/lib/IR/Globals.cpp
@@ -352,11 +352,15 @@
 GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
                                LinkageTypes Link, Constant *InitVal,
                                const Twine &Name, GlobalVariable *Before,
-                               ThreadLocalMode TLMode, unsigned AddressSpace,
+                               ThreadLocalMode TLMode,
+                               Optional<unsigned> AddressSpace,
                                bool isExternallyInitialized)
     : GlobalObject(Ty, Value::GlobalVariableVal,
                    OperandTraits<GlobalVariable>::op_begin(this),
-                   InitVal != nullptr, Link, Name, AddressSpace),
+                   InitVal != nullptr, Link, Name,
+                   AddressSpace
+                       ? *AddressSpace
+                       : M.getDataLayout().getDefaultGlobalsAddressSpace()),
       isConstantGlobal(constant),
       isExternallyInitializedConstant(isExternallyInitialized) {
   assert(!Ty->isFunctionTy() && PointerType::isValidElementType(Ty) &&
diff --git a/llvm/test/Assembler/invalid-datalayout-globals-addrspace.ll b/llvm/test/Assembler/invalid-datalayout-globals-addrspace.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Assembler/invalid-datalayout-globals-addrspace.ll
@@ -0,0 +1,4 @@
+; RUN: not --crash llvm-as < %s 2>&1 | FileCheck %s
+
+; CHECK: Invalid address space, must be a 24-bit integer
+target datalayout = "G16777216"
diff --git a/llvm/unittests/IR/DataLayoutTest.cpp b/llvm/unittests/IR/DataLayoutTest.cpp
--- a/llvm/unittests/IR/DataLayoutTest.cpp
+++ b/llvm/unittests/IR/DataLayoutTest.cpp
@@ -7,7 +7,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
 #include "llvm/IR/Type.h"
 #include "gtest/gtest.h"
 
@@ -56,4 +58,35 @@
             DL.getValueOrABITypeAlignment(MaybeAlign(), FourByteAlignType));
 }
 
-}  // anonymous namespace
+TEST(DataLayoutTest, GlobalsAddressSpace) {
+  // When not explicitly defined the globals address space should be zero:
+  EXPECT_EQ(DataLayout("").getDefaultGlobalsAddressSpace(), 0u);
+  EXPECT_EQ(DataLayout("P1-A2").getDefaultGlobalsAddressSpace(), 0u);
+  EXPECT_EQ(DataLayout("G2").getDefaultGlobalsAddressSpace(), 2u);
+  // Check that creating a GlobalVariable without an explicit address space
+  // in a module with a default globals address space respects that default:
+  LLVMContext Context;
+  std::unique_ptr<Module> M(new Module("MyModule", Context));
+  // Default is globals in address space zero:
+  auto *Int32 = Type::getInt32Ty(Context);
+  auto *DefaultGlobal1 = new GlobalVariable(
+      *M, Int32, false, GlobalValue::ExternalLinkage, nullptr);
+  EXPECT_EQ(DefaultGlobal1->getAddressSpace(), 0u);
+  auto *ExplicitGlobal1 = new GlobalVariable(
+      *M, Int32, false, GlobalValue::ExternalLinkage, nullptr, "", nullptr,
+      GlobalValue::NotThreadLocal, 123);
+  EXPECT_EQ(ExplicitGlobal1->getAddressSpace(), 123u);
+
+  // When using a datalayout with the global address space set to 200, global
+  // variables should default to 200
+  M->setDataLayout("G200");
+  auto *DefaultGlobal2 = new GlobalVariable(
+      *M, Int32, false, GlobalValue::ExternalLinkage, nullptr);
+  EXPECT_EQ(DefaultGlobal2->getAddressSpace(), 200u);
+  auto *ExplicitGlobal2 = new GlobalVariable(
+      *M, Int32, false, GlobalValue::ExternalLinkage, nullptr, "", nullptr,
+      GlobalValue::NotThreadLocal, 123);
+  EXPECT_EQ(ExplicitGlobal2->getAddressSpace(), 123u);
+}
+
+} // anonymous namespace