Index: cfe/trunk/include/clang/Basic/TargetInfo.h
===================================================================
--- cfe/trunk/include/clang/Basic/TargetInfo.h
+++ cfe/trunk/include/clang/Basic/TargetInfo.h
@@ -542,7 +542,9 @@
 
   /// getMinGlobalAlign - Return the minimum alignment of a global variable,
   /// unless its alignment is explicitly reduced via attributes.
-  unsigned getMinGlobalAlign() const { return MinGlobalAlign; }
+  virtual unsigned getMinGlobalAlign (uint64_t) const {
+    return MinGlobalAlign;
+  }
 
   /// Return the largest alignment for which a suitably-sized allocation with
   /// '::operator new(size_t)' is guaranteed to produce a correctly-aligned
Index: cfe/trunk/lib/AST/ASTContext.cpp
===================================================================
--- cfe/trunk/lib/AST/ASTContext.cpp
+++ cfe/trunk/lib/AST/ASTContext.cpp
@@ -1600,8 +1600,10 @@
       if (BaseT.getQualifiers().hasUnaligned())
         Align = Target->getCharWidth();
       if (const auto *VD = dyn_cast<VarDecl>(D)) {
-        if (VD->hasGlobalStorage() && !ForAlignof)
-          Align = std::max(Align, getTargetInfo().getMinGlobalAlign());
+        if (VD->hasGlobalStorage() && !ForAlignof) {
+          uint64_t TypeSize = getTypeSize(T.getTypePtr());
+          Align = std::max(Align, getTargetInfo().getMinGlobalAlign(TypeSize));
+        }
       }
     }
 
@@ -2239,7 +2241,8 @@
 /// getAlignOfGlobalVar - Return the alignment in bits that should be given
 /// to a global variable of the specified type.
 unsigned ASTContext::getAlignOfGlobalVar(QualType T) const {
-  return std::max(getTypeAlign(T), getTargetInfo().getMinGlobalAlign());
+  uint64_t TypeSize = getTypeSize(T.getTypePtr());
+  return std::max(getTypeAlign(T), getTargetInfo().getMinGlobalAlign(TypeSize));
 }
 
 /// getAlignOfGlobalVarInChars - Return the alignment in characters that
Index: cfe/trunk/lib/Basic/Targets/AArch64.h
===================================================================
--- cfe/trunk/lib/Basic/Targets/AArch64.h
+++ cfe/trunk/lib/Basic/Targets/AArch64.h
@@ -129,6 +129,8 @@
                         MacroBuilder &Builder) const override;
   TargetInfo::CallingConvKind
   getCallingConvKind(bool ClangABICompat4) const override;
+
+  unsigned getMinGlobalAlign(uint64_t TypeSize) const override;
 };
 
 // ARM64 MinGW target
Index: cfe/trunk/lib/Basic/Targets/AArch64.cpp
===================================================================
--- cfe/trunk/lib/Basic/Targets/AArch64.cpp
+++ cfe/trunk/lib/Basic/Targets/AArch64.cpp
@@ -551,6 +551,23 @@
   return CCK_MicrosoftWin64;
 }
 
+unsigned MicrosoftARM64TargetInfo::getMinGlobalAlign(uint64_t TypeSize) const {
+  unsigned Align = WindowsARM64TargetInfo::getMinGlobalAlign(TypeSize);
+
+  // MSVC does size based alignment for arm64 based on alignment section in
+  // below document, replicate that to keep alignment consistent with object
+  // files compiled by MSVC.
+  // https://docs.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions
+  if (TypeSize >= 512) {              // TypeSize >= 64 bytes
+    Align = std::max(Align, 128u);    // align type at least 16 bytes
+  } else if (TypeSize >= 64) {        // TypeSize >= 8 bytes
+    Align = std::max(Align, 64u);     // align type at least 8 butes
+  } else if (TypeSize >= 16) {        // TypeSize >= 2 bytes
+    Align = std::max(Align, 32u);     // align type at least 4 bytes
+  }
+  return Align;
+}
+
 MinGWARM64TargetInfo::MinGWARM64TargetInfo(const llvm::Triple &Triple,
                                            const TargetOptions &Opts)
     : WindowsARM64TargetInfo(Triple, Opts) {
Index: cfe/trunk/lib/Basic/Targets/NVPTX.cpp
===================================================================
--- cfe/trunk/lib/Basic/Targets/NVPTX.cpp
+++ cfe/trunk/lib/Basic/Targets/NVPTX.cpp
@@ -119,7 +119,7 @@
   LongAlign = HostTarget->getLongAlign();
   LongLongWidth = HostTarget->getLongLongWidth();
   LongLongAlign = HostTarget->getLongLongAlign();
-  MinGlobalAlign = HostTarget->getMinGlobalAlign();
+  MinGlobalAlign = HostTarget->getMinGlobalAlign(/* TypeSize = */ 0);
   NewAlign = HostTarget->getNewAlign();
   DefaultAlignForAttributeAligned =
       HostTarget->getDefaultAlignForAttributeAligned();
Index: cfe/trunk/test/CodeGen/arm64-microsoft-struct-align.cpp
===================================================================
--- cfe/trunk/test/CodeGen/arm64-microsoft-struct-align.cpp
+++ cfe/trunk/test/CodeGen/arm64-microsoft-struct-align.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple aarch64-windows -ffreestanding -emit-llvm -O0 \
+// RUN: -x c++ -o - %s | FileCheck %s
+
+struct size1 { char str[1]; };
+struct size2 { char str[2]; };
+struct size7 { char str[4]; };
+struct size8 { char str[8]; };
+struct size63 { char str[63]; };
+struct size64 { char str[64]; };
+
+struct size1 s1;
+// CHECK: @"?s1@@3Usize1@@A" = dso_local global %struct.size1 zeroinitializer, align 1
+
+struct size2 s2;
+// CHECK: @"?s2@@3Usize2@@A" = dso_local global %struct.size2 zeroinitializer, align 4
+
+struct size7 s7;
+// CHECK: @"?s7@@3Usize7@@A" = dso_local global %struct.size7 zeroinitializer, align 4
+
+struct size8 s8;
+// CHECK: @"?s8@@3Usize8@@A" = dso_local global %struct.size8 zeroinitializer, align 8
+
+struct size63 s63;
+// CHECK: @"?s63@@3Usize63@@A" = dso_local global %struct.size63 zeroinitializer, align 8
+
+struct size64 s64;
+// CHECK: @"?s64@@3Usize64@@A" = dso_local global %struct.size64 zeroinitializer, align 16