diff --git a/Misc/NEWS.d/next/Build/2026-09-11-19-37-05.gh-issue-101525.DGIpL3.rst b/Misc/NEWS.d/next/Build/2026-09-11-19-37-05.gh-issue-101525.DGIpL3.rst
new file mode 100644
index 00000000000000..f7394954ecda89
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2026-09-11-19-37-05.gh-issue-101525.DGIpL3.rst
@@ -0,0 +1,2 @@
+When using :option:`--enable-bolt`, enable safe identical code folding on
+BOLT versions new enough to support it (LLVM 20+).
diff --git a/configure b/configure
index 1115be256afb49..63444fcf8ea08a 100755
--- a/configure
+++ b/configure
@@ -9739,6 +9739,63 @@ printf "%s\n" "\"Found merge-fdata\"" >&6; }
   else
     as_fn_error $? "merge-fdata is required for a --enable-bolt build but could not be found." "$LINENO" 5
   fi
+
+  py_bolt_icf_flag="-icf=safe"
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether ${LLVM_BOLT} supports safe identical code folding" >&5
+printf %s "checking whether ${LLVM_BOLT} supports safe identical code folding... " >&6; }
+if test ${py_cv_bolt_icf_safe+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e)
+      save_CFLAGS=$CFLAGS
+save_CPPFLAGS=$CPPFLAGS
+save_LDFLAGS=$LDFLAGS
+save_LIBS=$LIBS
+
+
+        CFLAGS="$CFLAGS_NODIST"
+        LDFLAGS="$LDFLAGS_NODIST"
+        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main (void)
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  py_cv_bolt_icf_safe=no
+           ${LLVM_BOLT} -icf=safe -o conftest.bolt conftest$EXEEXT >&5 2>&1            && py_cv_bolt_icf_safe=yes
+else case e in #(
+  e) { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
+as_fn_error $? "could not compile empty test program
+See 'config.log' for more details" "$LINENO" 5; } ;;
+esac
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+
+CFLAGS=$save_CFLAGS
+CPPFLAGS=$save_CPPFLAGS
+LDFLAGS=$save_LDFLAGS
+LIBS=$save_LIBS
+
+
+
+   ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $py_cv_bolt_icf_safe" >&5
+printf "%s\n" "$py_cv_bolt_icf_safe" >&6; }
+  if test "$py_cv_bolt_icf_safe" = no; then
+    py_bolt_icf_flag=""
+  fi
 fi
 
 
@@ -9780,7 +9837,7 @@ printf "%s\n" "$BOLT_INSTRUMENT_FLAGS" >&6; }
 printf %s "checking BOLT_APPLY_FLAGS... " >&6; }
 if test -z "${BOLT_APPLY_FLAGS}"
 then
-  BOLT_APPLY_FLAGS=" ${BOLT_COMMON_FLAGS} -reorder-blocks=ext-tsp -reorder-functions=cdsort -split-functions -icf=0 -inline-all -split-eh -reorder-functions-use-hot-size -peepholes=none -jump-tables=aggressive -inline-ap -indirect-call-promotion=all -dyno-stats -use-gnu-stack -frame-opt=hot "
+  BOLT_APPLY_FLAGS=" ${BOLT_COMMON_FLAGS} -reorder-blocks=ext-tsp -reorder-functions=cdsort -split-functions ${py_bolt_icf_flag} -inline-all -split-eh -reorder-functions-use-hot-size -peepholes=none -jump-tables=aggressive -inline-ap -indirect-call-promotion=all -dyno-stats -use-gnu-stack -frame-opt=hot "
 
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $BOLT_APPLY_FLAGS" >&5
diff --git a/configure.ac b/configure.ac
index 902a822e43a42f..fa3fa639d1b68d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2230,6 +2230,27 @@ if test "$Py_BOLT" = 'true' ; then
   else
     AC_MSG_ERROR([merge-fdata is required for a --enable-bolt build but could not be found.])
   fi
+
+  py_bolt_icf_flag="-icf=safe"
+  AC_CACHE_CHECK(
+    [whether ${LLVM_BOLT} supports safe identical code folding],
+    [py_cv_bolt_icf_safe],
+    [
+      WITH_SAVE_ENV([
+        CFLAGS="$CFLAGS_NODIST"
+        LDFLAGS="$LDFLAGS_NODIST"
+        AC_LINK_IFELSE(
+          [AC_LANG_PROGRAM([], [])],
+          [py_cv_bolt_icf_safe=no
+           ${LLVM_BOLT} -icf=safe -o conftest.bolt conftest$EXEEXT >&AS_MESSAGE_LOG_FD 2>&1 dnl
+           && py_cv_bolt_icf_safe=yes],
+          [AC_MSG_FAILURE([could not compile empty test program])])
+      ])
+    ]
+  )
+  if test "$py_cv_bolt_icf_safe" = no; then
+    py_bolt_icf_flag=""
+  fi
 fi
 
 dnl Enable BOLT of libpython if built and used by the python3 binary.
@@ -2289,7 +2310,7 @@ then
      -reorder-blocks=ext-tsp
      -reorder-functions=cdsort
      -split-functions
-     -icf=0
+     ${py_bolt_icf_flag}
      -inline-all
      -split-eh
      -reorder-functions-use-hot-size