diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -41,6 +41,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/TargetCXXABI.h"
+#include "clang/Basic/TargetInfo.h"
 #include "clang/Basic/XRayLists.h"
 #include "llvm/ADT/APSInt.h"
 #include "llvm/ADT/ArrayRef.h"
@@ -128,7 +129,6 @@
 class Stmt;
 class StoredDeclsMap;
 class TargetAttr;
-class TargetInfo;
 class TemplateDecl;
 class TemplateParameterList;
 class TemplateTemplateParmDecl;
@@ -750,7 +750,8 @@
   /// getRealTypeForBitwidth -
   /// sets floating point QualTy according to specified bitwidth.
   /// Returns empty type if there is no appropriate target types.
-  QualType getRealTypeForBitwidth(unsigned DestWidth, bool ExplicitIEEE) const;
+  QualType getRealTypeForBitwidth(unsigned DestWidth,
+                                  TargetInfo::RealType ExplicitType) const;
 
   bool AtomicUsesUnsupportedLibcall(const AtomicExpr *E) const;
 
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
@@ -398,10 +398,8 @@
   /// Return floating point type with specified width. On PPC, there are
   /// three possible types for 128-bit floating point: "PPC double-double",
   /// IEEE 754R quad precision, and "long double" (which under the covers
-  /// is represented as one of those two). At this time, there is no support
-  /// for an explicit "PPC double-double" type (i.e. __ibm128) so we only
-  /// need to differentiate between "long double" and IEEE quad precision.
-  RealType getRealTypeByWidth(unsigned BitWidth, bool ExplicitIEEE) const;
+  /// is represented as one of those two).
+  RealType getRealTypeByWidth(unsigned BitWidth, RealType ExplicitType) const;
 
   /// Return the alignment (in bits) of the specified integer type enum.
   ///
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -11260,10 +11260,11 @@
 /// getRealTypeForBitwidth -
 /// sets floating point QualTy according to specified bitwidth.
 /// Returns empty type if there is no appropriate target types.
-QualType ASTContext::getRealTypeForBitwidth(unsigned DestWidth,
-                                            bool ExplicitIEEE) const {
+QualType
+ASTContext::getRealTypeForBitwidth(unsigned DestWidth,
+                                   TargetInfo::RealType ExplicitType) const {
   TargetInfo::RealType Ty =
-      getTargetInfo().getRealTypeByWidth(DestWidth, ExplicitIEEE);
+      getTargetInfo().getRealTypeByWidth(DestWidth, ExplicitType);
   switch (Ty) {
   case TargetInfo::Float:
     return FloatTy;
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
@@ -279,8 +279,8 @@
   return NoInt;
 }
 
-TargetInfo::RealType TargetInfo::getRealTypeByWidth(unsigned BitWidth,
-                                                    bool ExplicitIEEE) const {
+TargetInfo::RealType
+TargetInfo::getRealTypeByWidth(unsigned BitWidth, RealType ExplicitType) const {
   if (getFloatWidth() == BitWidth)
     return Float;
   if (getDoubleWidth() == BitWidth)
@@ -294,13 +294,10 @@
   case 128:
     // The caller explicitly asked for an IEEE compliant type but we still
     // have to check if the target supports it.
-    if (ExplicitIEEE)
+    if (ExplicitType == Float128)
       return hasFloat128Type() ? Float128 : NoFloat;
-    if (&getLongDoubleFormat() == &llvm::APFloat::PPCDoubleDouble() ||
-        &getLongDoubleFormat() == &llvm::APFloat::IEEEquad())
-      return LongDouble;
-    if (hasFloat128Type())
-      return Float128;
+    if (ExplicitType == Ibm128 || ExplicitType == LongDouble)
+      return ExplicitType;
     break;
   }
 
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4203,9 +4203,10 @@
 /// attribute.
 static void parseModeAttrArg(Sema &S, StringRef Str, unsigned &DestWidth,
                              bool &IntegerMode, bool &ComplexMode,
-                             bool &ExplicitIEEE) {
+                             TargetInfo::RealType &ExplicitType) {
   IntegerMode = true;
   ComplexMode = false;
+  ExplicitType = TargetInfo::NoFloat;
   switch (Str.size()) {
   case 2:
     switch (Str[0]) {
@@ -4225,13 +4226,17 @@
       DestWidth = 96;
       break;
     case 'K': // KFmode - IEEE quad precision (__float128)
-      ExplicitIEEE = true;
+      ExplicitType = TargetInfo::Float128;
       DestWidth = Str[1] == 'I' ? 0 : 128;
       break;
     case 'T':
-      ExplicitIEEE = false;
+      ExplicitType = TargetInfo::LongDouble;
       DestWidth = 128;
       break;
+    case 'I':
+      ExplicitType = TargetInfo::Ibm128;
+      DestWidth = Str[1] == 'I' ? 0 : 128;
+      break;
     }
     if (Str[1] == 'F') {
       IntegerMode = false;
@@ -4290,7 +4295,7 @@
   unsigned DestWidth = 0;
   bool IntegerMode = true;
   bool ComplexMode = false;
-  bool ExplicitIEEE = false;
+  TargetInfo::RealType ExplicitType = TargetInfo::NoFloat;
   llvm::APInt VectorSize(64, 0);
   if (Str.size() >= 4 && Str[0] == 'V') {
     // Minimal length of vector mode is 4: 'V' + NUMBER(>=1) + TYPE(>=2).
@@ -4303,7 +4308,7 @@
         !Str.substr(1, VectorStringLength).getAsInteger(10, VectorSize) &&
         VectorSize.isPowerOf2()) {
       parseModeAttrArg(*this, Str.substr(VectorStringLength + 1), DestWidth,
-                       IntegerMode, ComplexMode, ExplicitIEEE);
+                       IntegerMode, ComplexMode, ExplicitType);
       // Avoid duplicate warning from template instantiation.
       if (!InInstantiation)
         Diag(AttrLoc, diag::warn_vector_mode_deprecated);
@@ -4314,7 +4319,7 @@
 
   if (!VectorSize)
     parseModeAttrArg(*this, Str, DestWidth, IntegerMode, ComplexMode,
-                     ExplicitIEEE);
+                     ExplicitType);
 
   // FIXME: Sync this with InitializePredefinedMacros; we need to match int8_t
   // and friends, at least with glibc.
@@ -4380,7 +4385,7 @@
     NewElemTy = Context.getIntTypeForBitwidth(DestWidth,
                                               OldElemTy->isSignedIntegerType());
   else
-    NewElemTy = Context.getRealTypeForBitwidth(DestWidth, ExplicitIEEE);
+    NewElemTy = Context.getRealTypeForBitwidth(DestWidth, ExplicitType);
 
   if (NewElemTy.isNull()) {
     Diag(AttrLoc, diag::err_machine_mode) << 1 /*Unsupported*/ << Name;
diff --git a/clang/test/Sema/attr-mode.c b/clang/test/Sema/attr-mode.c
--- a/clang/test/Sema/attr-mode.c
+++ b/clang/test/Sema/attr-mode.c
@@ -92,6 +92,12 @@
 void f_ft128_complex_arg(_Complex long double *x);
 void test_TFtype(f128ibm *a) { f_ft128_arg (a); }
 void test_TCtype(c128ibm *a) { f_ft128_complex_arg (a); }
+typedef float w128ibm __attribute__((mode(IF)));
+typedef _Complex float cw128ibm __attribute__((mode(IC)));
+void f_ibm128_arg(__ibm128 *x);
+void f_ibm128_complex_arg(_Complex __ibm128 *x);
+void test_IFtype(w128ibm *a) { f_ibm128_arg(a); }
+void test_ICtype(cw128ibm *a) { f_ibm128_complex_arg(a); }
 #elif TEST_F128_PPC64
 typedef int invalid_7 __attribute((mode(KF))); // expected-error{{type of machine mode does not match type of base type}}
 typedef int invalid_8 __attribute((mode(KI))); // expected-error{{unknown machine mode}}