diff --git a/clang/include/clang/Basic/TargetInfo.h b/clang/include/clang/Basic/TargetInfo.h
--- a/clang/include/clang/Basic/TargetInfo.h
+++ b/clang/include/clang/Basic/TargetInfo.h
@@ -96,6 +96,7 @@
   unsigned char LongAccumScale;
 
   unsigned char SuitableAlign;
+  unsigned char GuaranteedAlign;
   unsigned char DefaultAlignForAttributeAligned;
   unsigned char MinGlobalAlign;
 
@@ -581,10 +582,16 @@
   /// Determine whether constrained floating point is supported on this target.
   virtual bool hasStrictFP() const { return HasStrictFP; }
 
-  /// Return the alignment that is suitable for storing any
-  /// object with a fundamental alignment requirement.
+  /// Return the alignment that is the largest alignment ever used for any
+  /// scalar/SIMD data type on the target machine you are compiling for
+  /// (including types with an extended alignment requirement).
   unsigned getSuitableAlign() const { return SuitableAlign; }
 
+  /// Return the alignment is meant to be the biggest alignment guaranteed by
+  /// the memory allocation facilities of the system. In other words,
+  /// the fundamental alignment.
+  unsigned getGuaranteedAlign() const { return GuaranteedAlign; }
+
   /// Return the default alignment for __attribute__((aligned)) on
   /// this target, to be used if no alignment value is specified.
   unsigned getDefaultAlignForAttributeAligned() const {
diff --git a/clang/lib/Basic/TargetInfo.cpp b/clang/lib/Basic/TargetInfo.cpp
--- a/clang/lib/Basic/TargetInfo.cpp
+++ b/clang/lib/Basic/TargetInfo.cpp
@@ -61,7 +61,7 @@
   AccumScale = 15;
   LongAccumScale = 31;
 
-  SuitableAlign = 64;
+  GuaranteedAlign = SuitableAlign = 64;
   DefaultAlignForAttributeAligned = 128;
   MinGlobalAlign = 0;
   // From the glibc documentation, on GNU systems, malloc guarantees 16-byte
diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -67,7 +67,7 @@
   MaxAtomicInlineWidth = 128;
   MaxAtomicPromoteWidth = 128;
 
-  LongDoubleWidth = LongDoubleAlign = SuitableAlign = 128;
+  LongDoubleWidth = LongDoubleAlign = GuaranteedAlign = SuitableAlign = 128;
   LongDoubleFormat = &llvm::APFloat::IEEEquad();
 
   BFloat16Width = BFloat16Align = 16;
@@ -835,7 +835,7 @@
   WCharType = SignedInt;
   UseSignedCharForObjCBool = false;
 
-  LongDoubleWidth = LongDoubleAlign = SuitableAlign = 64;
+  LongDoubleWidth = LongDoubleAlign = GuaranteedAlign = SuitableAlign = 64;
   LongDoubleFormat = &llvm::APFloat::IEEEdouble();
 
   UseZeroLengthBitfieldAlignment = false;
diff --git a/clang/lib/Basic/Targets/ARC.h b/clang/lib/Basic/Targets/ARC.h
--- a/clang/lib/Basic/Targets/ARC.h
+++ b/clang/lib/Basic/Targets/ARC.h
@@ -27,7 +27,7 @@
       : TargetInfo(Triple) {
     NoAsmVariants = true;
     LongLongAlign = 32;
-    SuitableAlign = 32;
+    GuaranteedAlign = SuitableAlign = 32;
     DoubleAlign = LongDoubleAlign = 32;
     SizeType = UnsignedInt;
     PtrDiffType = SignedInt;
diff --git a/clang/lib/Basic/Targets/ARM.cpp b/clang/lib/Basic/Targets/ARM.cpp
--- a/clang/lib/Basic/Targets/ARM.cpp
+++ b/clang/lib/Basic/Targets/ARM.cpp
@@ -24,7 +24,8 @@
 void ARMTargetInfo::setABIAAPCS() {
   IsAAPCS = true;
 
-  DoubleAlign = LongLongAlign = LongDoubleAlign = SuitableAlign = 64;
+  DoubleAlign = LongLongAlign = LongDoubleAlign = GuaranteedAlign =
+      SuitableAlign = 64;
   BFloat16Width = BFloat16Align = 16;
   BFloat16Format = &llvm::APFloat::BFloat();
 
@@ -74,9 +75,11 @@
   IsAAPCS = false;
 
   if (IsAAPCS16)
-    DoubleAlign = LongLongAlign = LongDoubleAlign = SuitableAlign = 64;
+    DoubleAlign = LongLongAlign = LongDoubleAlign = GuaranteedAlign =
+        SuitableAlign = 64;
   else
-    DoubleAlign = LongLongAlign = LongDoubleAlign = SuitableAlign = 32;
+    DoubleAlign = LongLongAlign = LongDoubleAlign = GuaranteedAlign =
+        SuitableAlign = 32;
   BFloat16Width = BFloat16Align = 16;
   BFloat16Format = &llvm::APFloat::BFloat();
 
diff --git a/clang/lib/Basic/Targets/AVR.h b/clang/lib/Basic/Targets/AVR.h
--- a/clang/lib/Basic/Targets/AVR.h
+++ b/clang/lib/Basic/Targets/AVR.h
@@ -35,7 +35,7 @@
     LongAlign = 8;
     LongLongWidth = 64;
     LongLongAlign = 8;
-    SuitableAlign = 8;
+    GuaranteedAlign = SuitableAlign = 8;
     DefaultAlignForAttributeAligned = 8;
     HalfWidth = 16;
     HalfAlign = 8;
diff --git a/clang/lib/Basic/Targets/MSP430.h b/clang/lib/Basic/Targets/MSP430.h
--- a/clang/lib/Basic/Targets/MSP430.h
+++ b/clang/lib/Basic/Targets/MSP430.h
@@ -39,7 +39,7 @@
     DoubleAlign = LongDoubleAlign = 16;
     PointerWidth = 16;
     PointerAlign = 16;
-    SuitableAlign = 16;
+    GuaranteedAlign = SuitableAlign = 16;
     SizeType = UnsignedInt;
     IntMaxType = SignedLongLong;
     IntPtrType = SignedInt;
diff --git a/clang/lib/Basic/Targets/Mips.h b/clang/lib/Basic/Targets/Mips.h
--- a/clang/lib/Basic/Targets/Mips.h
+++ b/clang/lib/Basic/Targets/Mips.h
@@ -125,7 +125,7 @@
     PointerWidth = PointerAlign = 32;
     PtrDiffType = SignedInt;
     SizeType = UnsignedInt;
-    SuitableAlign = 64;
+    GuaranteedAlign = SuitableAlign = 64;
   }
 
   void setN32N64ABITypes() {
@@ -136,7 +136,7 @@
       LongDoubleFormat = &llvm::APFloat::IEEEdouble();
     }
     MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 64;
-    SuitableAlign = 128;
+    GuaranteedAlign = SuitableAlign = 128;
   }
 
   void setN64ABITypes() {
diff --git a/clang/lib/Basic/Targets/PPC.h b/clang/lib/Basic/Targets/PPC.h
--- a/clang/lib/Basic/Targets/PPC.h
+++ b/clang/lib/Basic/Targets/PPC.h
@@ -78,7 +78,7 @@
 public:
   PPCTargetInfo(const llvm::Triple &Triple, const TargetOptions &)
       : TargetInfo(Triple) {
-    SuitableAlign = 128;
+    GuaranteedAlign = SuitableAlign = 128;
     SimdDefaultAlign = 128;
     LongDoubleWidth = LongDoubleAlign = 128;
     LongDoubleFormat = &llvm::APFloat::PPCDoubleDouble();
@@ -370,7 +370,7 @@
       SizeType = UnsignedLong;
       PtrDiffType = SignedLong;
       IntPtrType = SignedLong;
-      SuitableAlign = 64;
+      GuaranteedAlign = 64;
       LongDoubleWidth = 64;
       LongDoubleAlign = DoubleAlign = 32;
       LongDoubleFormat = &llvm::APFloat::IEEEdouble();
@@ -409,7 +409,7 @@
     if (Triple.isOSAIX()) {
       // TODO: Set appropriate ABI for AIX platform.
       DataLayout = "E-m:a-i64:64-n32:64";
-      SuitableAlign = 64;
+      GuaranteedAlign = 64;
       LongDoubleWidth = 64;
       LongDoubleAlign = DoubleAlign = 32;
       LongDoubleFormat = &llvm::APFloat::IEEEdouble();
diff --git a/clang/lib/Basic/Targets/RISCV.h b/clang/lib/Basic/Targets/RISCV.h
--- a/clang/lib/Basic/Targets/RISCV.h
+++ b/clang/lib/Basic/Targets/RISCV.h
@@ -39,7 +39,7 @@
     LongDoubleWidth = 128;
     LongDoubleAlign = 128;
     LongDoubleFormat = &llvm::APFloat::IEEEquad();
-    SuitableAlign = 128;
+    GuaranteedAlign = SuitableAlign = 128;
     WCharType = SignedInt;
     WIntType = UnsignedInt;
   }
diff --git a/clang/lib/Basic/Targets/Sparc.h b/clang/lib/Basic/Targets/Sparc.h
--- a/clang/lib/Basic/Targets/Sparc.h
+++ b/clang/lib/Basic/Targets/Sparc.h
@@ -214,7 +214,7 @@
     // aligned. The SPARCv9 SCD 2.4.1 says 16-byte aligned.
     LongDoubleWidth = 128;
     LongDoubleAlign = 128;
-    SuitableAlign = 128;
+    GuaranteedAlign = SuitableAlign = 128;
     LongDoubleFormat = &llvm::APFloat::IEEEquad();
     MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 64;
   }
diff --git a/clang/lib/Basic/Targets/TCE.h b/clang/lib/Basic/Targets/TCE.h
--- a/clang/lib/Basic/Targets/TCE.h
+++ b/clang/lib/Basic/Targets/TCE.h
@@ -58,7 +58,7 @@
     IntAlign = 32;
     LongAlign = LongLongAlign = 32;
     PointerAlign = 32;
-    SuitableAlign = 32;
+    GuaranteedAlign = SuitableAlign = 32;
     SizeType = UnsignedInt;
     IntMaxType = SignedLong;
     IntPtrType = SignedInt;
diff --git a/clang/lib/Basic/Targets/WebAssembly.h b/clang/lib/Basic/Targets/WebAssembly.h
--- a/clang/lib/Basic/Targets/WebAssembly.h
+++ b/clang/lib/Basic/Targets/WebAssembly.h
@@ -46,7 +46,7 @@
   explicit WebAssemblyTargetInfo(const llvm::Triple &T, const TargetOptions &)
       : TargetInfo(T) {
     NoAsmVariants = true;
-    SuitableAlign = 128;
+    GuaranteedAlign = SuitableAlign = 128;
     LargeArrayMinWidth = 128;
     LargeArrayAlign = 128;
     SimdDefaultAlign = 128;
diff --git a/clang/lib/Basic/Targets/X86.h b/clang/lib/Basic/Targets/X86.h
--- a/clang/lib/Basic/Targets/X86.h
+++ b/clang/lib/Basic/Targets/X86.h
@@ -381,7 +381,7 @@
     DoubleAlign = LongLongAlign = 32;
     LongDoubleWidth = 96;
     LongDoubleAlign = 32;
-    SuitableAlign = 128;
+    GuaranteedAlign = SuitableAlign = 128;
     resetDataLayout(Triple.isOSBinFormatMachO() ?
                     "e-m:o-p:32:32-p270:32:32-p271:32:32-p272:64:64-f64:32:64-"
                     "f80:32-n8:16:32-S128" :
@@ -481,7 +481,7 @@
       : DarwinTargetInfo<X86_32TargetInfo>(Triple, Opts) {
     LongDoubleWidth = 128;
     LongDoubleAlign = 128;
-    SuitableAlign = 128;
+    GuaranteedAlign = SuitableAlign = 128;
     MaxVectorAlign = 256;
     // The watchOS simulator uses the builtin bool type for Objective-C.
     llvm::Triple T = llvm::Triple(Triple);
@@ -655,7 +655,7 @@
     LongDoubleAlign = 128;
     LargeArrayMinWidth = 128;
     LargeArrayAlign = 128;
-    SuitableAlign = 128;
+    GuaranteedAlign = SuitableAlign = 128;
     SizeType = IsX32 ? UnsignedInt : UnsignedLong;
     PtrDiffType = IsX32 ? SignedInt : SignedLong;
     IntPtrType = IsX32 ? SignedInt : SignedLong;
@@ -893,7 +893,7 @@
 public:
   AndroidX86_32TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
       : LinuxTargetInfo<X86_32TargetInfo>(Triple, Opts) {
-    SuitableAlign = 32;
+    GuaranteedAlign = SuitableAlign = 32;
     LongDoubleWidth = 64;
     LongDoubleFormat = &llvm::APFloat::IEEEdouble();
   }
diff --git a/clang/lib/Basic/Targets/XCore.h b/clang/lib/Basic/Targets/XCore.h
--- a/clang/lib/Basic/Targets/XCore.h
+++ b/clang/lib/Basic/Targets/XCore.h
@@ -29,7 +29,7 @@
       : TargetInfo(Triple) {
     NoAsmVariants = true;
     LongLongAlign = 32;
-    SuitableAlign = 32;
+    GuaranteedAlign = SuitableAlign = 32;
     DoubleAlign = LongDoubleAlign = 32;
     SizeType = UnsignedInt;
     PtrDiffType = SignedInt;
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -882,7 +882,7 @@
 
   // Define __BIGGEST_ALIGNMENT__ to be compatible with gcc.
   Builder.defineMacro("__BIGGEST_ALIGNMENT__",
-                      Twine(TI.getSuitableAlign() / TI.getCharWidth()) );
+                      Twine(TI.getGuaranteedAlign() / TI.getCharWidth()));
 
   if (!LangOpts.CharIsSigned)
     Builder.defineMacro("__CHAR_UNSIGNED__");
diff --git a/clang/test/CodeGen/aix_alloca_align.c b/clang/test/CodeGen/aix_alloca_align.c
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGen/aix_alloca_align.c
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -triple=powerpc-ibm-aix-xcoff -S -emit-llvm < %s | \
+// RUN: FileCheck -check-prefix 32BIT %s
+
+// RUN: %clang_cc1 -triple=powerpc64-ibm-aix-xcoff -S -emit-llvm < %s | \
+// RUN: FileCheck -check-prefix 64BIT %s
+
+typedef long unsigned int size_t;
+extern void *alloca(size_t __size) __attribute__((__nothrow__));
+
+void foo() {
+  char *ptr1 = (char *)alloca(sizeof(char) * 9);
+  int *ptr2 = (int *)alloca(sizeof(int) * 9);
+  double *ptr3 = (double *)alloca(sizeof(double) * 9);
+}
+
+// 32BIT: %0 = alloca i8, i32 9, align 16
+// 32BIT: %1 = alloca i8, i32 36, align 16
+// 32BIT: %3 = alloca i8, i32 72, align 16
+
+// 64BIT: %0 = alloca i8, i64 9, align 16
+// 64BIT: %1 = alloca i8, i64 36, align 16
+// 64BIT: %3 = alloca i8, i64 72, align 16