Index: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticGroups.td
+++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td
@@ -59,6 +59,8 @@
                                                    UndefinedBoolConversion]>;
 def IntConversion : DiagGroup<"int-conversion">;
 def EnumConversion : DiagGroup<"enum-conversion">;
+def ImplicitIntConversion : DiagGroup<"implicit-int-conversion">;
+def ImplicitFloatConversion : DiagGroup<"implicit-float-conversion">;
 
 def FloatOverflowConversion : DiagGroup<"float-overflow-conversion">;
 def FloatZeroConversion : DiagGroup<"float-zero-conversion">;
@@ -709,6 +711,8 @@
                             FloatConversion,
                             Shorten64To32,
                             IntConversion,
+                            ImplicitIntConversion,
+                            ImplicitFloatConversion,
                             LiteralConversion,
                             NonLiteralNullConversion, // (1-1)->pointer (etc)
                             NullConversion, // NULL->non-pointer
Index: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3181,10 +3181,10 @@
   "implicit conversion from %0 to %1 is not permitted in C++">;
 def warn_impcast_float_precision : Warning<
   "implicit conversion loses floating-point precision: %0 to %1">,
-  InGroup<Conversion>, DefaultIgnore;
+  InGroup<ImplicitFloatConversion>, DefaultIgnore;
 def warn_impcast_float_result_precision : Warning<
   "implicit conversion when assigning computation result loses floating-point precision: %0 to %1">,
-  InGroup<Conversion>, DefaultIgnore;
+  InGroup<ImplicitFloatConversion>, DefaultIgnore;
 def warn_impcast_double_promotion : Warning<
   "implicit conversion increases floating-point precision: %0 to %1">,
   InGroup<DoublePromotion>, DefaultIgnore;
@@ -3196,10 +3196,10 @@
   InGroup<SignConversion>, DefaultIgnore;
 def warn_impcast_integer_precision : Warning<
   "implicit conversion loses integer precision: %0 to %1">,
-  InGroup<Conversion>, DefaultIgnore;
+  InGroup<ImplicitIntConversion>, DefaultIgnore;
 def warn_impcast_high_order_zero_bits : Warning<
   "higher order bits are zeroes after implicit conversion">,
-  InGroup<Conversion>, DefaultIgnore;
+  InGroup<ImplicitIntConversion>, DefaultIgnore;
 def warn_impcast_nonnegative_result : Warning<
   "the resulting value is always non-negative after implicit conversion">,
   InGroup<SignConversion>, DefaultIgnore;
Index: cfe/trunk/test/Sema/implicit-int-conversion.c
===================================================================
--- cfe/trunk/test/Sema/implicit-int-conversion.c
+++ cfe/trunk/test/Sema/implicit-int-conversion.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 %s -verify -Wconversion -Wno-implicit-int-conversion -DSMALL=char -DBIG=int -DNO_DIAG
+// RUN: %clang_cc1 %s -verify -Wno-conversion -Wimplicit-int-conversion -DSMALL=char -DBIG=int
+// RUN: %clang_cc1 %s -verify -Wconversion -Wno-implicit-float-conversion -DSMALL=float -DBIG=double -DNO_DIAG
+// RUN: %clang_cc1 %s -verify -Wno-conversion -Wimplicit-float-conversion -DSMALL=float -DBIG=double
+
+void f() {
+  SMALL a;
+  BIG b = 0;
+  a = b;
+#ifndef NO_DIAG
+  // expected-warning@-2 {{implicit conversion}}
+#else
+  // expected-no-diagnostics
+#endif
+}