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
@@ -297,11 +297,11 @@
     if (ExplicitType == FloatModeKind::Float128)
       return hasFloat128Type() ? FloatModeKind::Float128
                                : FloatModeKind::NoFloat;
-    if (&getLongDoubleFormat() == &llvm::APFloat::PPCDoubleDouble() ||
-        &getLongDoubleFormat() == &llvm::APFloat::IEEEquad())
-      return FloatModeKind::LongDouble;
-    if (hasFloat128Type())
-      return FloatModeKind::Float128;
+    if (ExplicitType == FloatModeKind::Ibm128)
+      return hasIbm128Type() ? FloatModeKind::Ibm128
+                             : FloatModeKind::NoFloat;
+    if (ExplicitType == FloatModeKind::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
@@ -4233,6 +4233,10 @@
       ExplicitType = FloatModeKind::LongDouble;
       DestWidth = 128;
       break;
+    case 'I':
+      ExplicitType = FloatModeKind::Ibm128;
+      DestWidth = Str[1] == 'I' ? 0 : 128;
+      break;
     }
     if (Str[1] == 'F') {
       IntegerMode = false;
diff --git a/clang/test/CodeGenCXX/ibm128-declarations.cpp b/clang/test/CodeGenCXX/ibm128-declarations.cpp
--- a/clang/test/CodeGenCXX/ibm128-declarations.cpp
+++ b/clang/test/CodeGenCXX/ibm128-declarations.cpp
@@ -59,6 +59,12 @@
   constexpr static __ibm128 mem = Q;
 };
 
+typedef float w128ibm __attribute__((mode(IF)));
+typedef _Complex float w128ibm_c __attribute__((mode(IC)));
+
+w128ibm icmode_self(w128ibm x) { return x; }
+w128ibm_c icmode_self_complex(w128ibm_c x) { return x; }
+
 int main(void) {
   __ibm128 lf;
   CTest ct(lf);
@@ -115,6 +121,9 @@
 // CHECK:   ret ppc_fp128 %2
 // CHECK: }
 
+// CHECK: define dso_local ppc_fp128 @_Z11icmode_selfg(ppc_fp128 %x)
+// CHECK: define dso_local { ppc_fp128, ppc_fp128 } @_Z19icmode_self_complexCg(ppc_fp128 %x.coerce0, ppc_fp128 %x.coerce1)
+
 // CHECK: define dso_local signext i32 @main()
 // CHECK: entry:
 // CHECK:   %0 = load ppc_fp128, ppc_fp128* %lf, align 16
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}}