Index: clang/lib/Format/WhitespaceManager.cpp
===================================================================
--- clang/lib/Format/WhitespaceManager.cpp
+++ clang/lib/Format/WhitespaceManager.cpp
@@ -909,8 +909,8 @@
 
     if (Style.ColumnLimit == 0)
       ChangeMaxColumn = UINT_MAX;
-    else if (Style.ColumnLimit >= Changes[i].TokenLength)
-      ChangeMaxColumn = Style.ColumnLimit - Changes[i].TokenLength;
+    else if (Style.ColumnLimit >= Changes[i].Tok->ColumnWidth)
+      ChangeMaxColumn = Style.ColumnLimit - Changes[i].Tok->ColumnWidth;
     else
       ChangeMaxColumn = ChangeMinColumn;
 
Index: clang/unittests/Format/FormatTestComments.cpp
===================================================================
--- clang/unittests/Format/FormatTestComments.cpp
+++ clang/unittests/Format/FormatTestComments.cpp
@@ -2856,6 +2856,13 @@
                "int a; //\n");
   verifyFormat("/**/   //\n"
                "int a; //\n");
+
+  // https://llvm.org/PR48280
+  EXPECT_EQ("int ab; // utf8 🐉\n"
+            "int a;  // line\n",
+            format("int ab; // long 🐉\n"
+                   "int a; // line\n",
+                   getLLVMStyleWithColumns(17)));
 }
 
 TEST_F(FormatTestComments, AlignsBlockCommentDecorations) {