diff --git a/lib/Basic/SourceManager.cpp b/lib/Basic/SourceManager.cpp
index 354bf7b..b91671a 100644
--- a/lib/Basic/SourceManager.cpp
+++ b/lib/Basic/SourceManager.cpp
@@ -560,10 +560,14 @@
 SourceLocation SourceManager::
 getInstantiationLocSlowCase(SourceLocation Loc) const {
   do {
-    std::pair<FileID, unsigned> LocInfo = getDecomposedLoc(Loc);
-    Loc = getSLocEntry(LocInfo.first).getInstantiation()
+    // Note: If Loc indicates an offset into a token that came from a macro
+    // expansion (e.g. the 5th character of the token) we do not want to add
+    // this offset when going to the instantiation location.  The instatiation
+    // location is the macro invocation, which the offset has nothing to do
+    // with.  This is unlike when we get the spelling loc, because the offset
+    // directly correspond to the token whose spelling we're inspecting.
+    Loc = getSLocEntry(getFileID(Loc)).getInstantiation()
                    .getInstantiationLocStart();
-    Loc = Loc.getFileLocWithOffset(LocInfo.second);
   } while (!Loc.isFileID());
 
   return Loc;
diff --git a/test/Misc/caret-diags-macros.c b/test/Misc/caret-diags-macros.c
index 80371a9..e138f59 100644
--- a/test/Misc/caret-diags-macros.c
+++ b/test/Misc/caret-diags-macros.c
@@ -24,3 +24,12 @@
   C;
 }
 
+
+// rdar://7597492
+#define sprintf(str, A, B) \
+__builtin___sprintf_chk (str, 0, 42, A, B)
+
+void baz(char *Msg) {
+  sprintf(Msg,  "  sizeof FoooLib            : =%3u\n",   12LL);
+}
+