diff --git a/media/gmp-clearkey/0.1/moz.build b/media/gmp-clearkey/0.1/moz.build
index 4dc7e8767889..a4200a76ac23 100644
--- a/media/gmp-clearkey/0.1/moz.build
+++ b/media/gmp-clearkey/0.1/moz.build
@@ -7,7 +7,7 @@
 with Files("**"):
     BUG_COMPONENT = ("Core", "Audio/Video: GMP")
 
-SharedLibrary("clearkey")
+GeckoSharedLibrary("clearkey", linkage=None)
 
 FINAL_TARGET = "dist/bin/gmp-clearkey/0.1"
 
diff --git a/memory/replace/logalloc/replay/moz.build b/memory/replace/logalloc/replay/moz.build
index 3e0c8c395aee..ca85f175570f 100644
--- a/memory/replace/logalloc/replay/moz.build
+++ b/memory/replace/logalloc/replay/moz.build
@@ -44,7 +44,19 @@ if CONFIG["MOZ_DMD"] or CONFIG["MOZ_PHC"]:
             "/mozglue/misc/StackWalk.h",
         ]
 
-if not CONFIG["MOZ_REPLACE_MALLOC_STATIC"]:
+if CONFIG["MOZ_REPLACE_MALLOC_STATIC"]:
+    UNIFIED_SOURCES += [
+        "/mfbt/double-conversion/double-conversion/bignum-dtoa.cc",
+        "/mfbt/double-conversion/double-conversion/bignum.cc",
+        "/mfbt/double-conversion/double-conversion/cached-powers.cc",
+        "/mfbt/double-conversion/double-conversion/double-to-string.cc",
+        "/mfbt/double-conversion/double-conversion/fast-dtoa.cc",
+        "/mfbt/double-conversion/double-conversion/fixed-dtoa.cc",
+        "/mfbt/double-conversion/double-conversion/string-to-double.cc",
+        "/mfbt/double-conversion/double-conversion/strtod.cc",
+        "/mozglue/misc/Printf.cpp",
+    ]
+else:
     SOURCES += [
         "../FdPrintf.cpp",
     ]
diff --git a/mfbt/tests/moz.build b/mfbt/tests/moz.build
index 5d08728f8492..9c8ebc838ced 100644
--- a/mfbt/tests/moz.build
+++ b/mfbt/tests/moz.build
@@ -91,9 +91,6 @@ if not CONFIG["MOZ_ASAN"]:
         ]
     )
 
-# Since we link directly with MFBT object files, define IMPL_MFBT
-DEFINES["IMPL_MFBT"] = True
-
 DisableStlWrapping()
 
 if CONFIG["CC_TYPE"] == "clang-cl":
@@ -103,7 +100,7 @@ if CONFIG["CC_TYPE"] == "clang-cl":
     ]
 
 USE_LIBS += [
-    "mfbt",
+    "mozglue",
 ]
 
 if CONFIG["CC_TYPE"] in ("clang", "gcc"):
diff --git a/mozglue/misc/Printf.h b/mozglue/misc/Printf.h
index e073a0d61cac..3f4fa2c1bb89 100644
--- a/mozglue/misc/Printf.h
+++ b/mozglue/misc/Printf.h
@@ -88,6 +88,8 @@ class PrintfTarget {
   bool MFBT_API appendIntOct(uint64_t);
   bool MFBT_API appendIntHex(uint64_t);
 
+  inline size_t emitted() { return mEmitted; }
+
  protected:
   MFBT_API PrintfTarget();
   virtual ~PrintfTarget() = default;
diff --git a/mozglue/misc/Sprintf.h b/mozglue/misc/Sprintf.h
index 14dcbe0c1dea..2017aad5dc54 100644
--- a/mozglue/misc/Sprintf.h
+++ b/mozglue/misc/Sprintf.h
@@ -11,19 +11,60 @@
 
 #include <stdio.h>
 #include <stdarg.h>
+#include <algorithm>
 
 #include "mozilla/Assertions.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/Printf.h"
 
 #ifdef __cplusplus
 
+#  ifndef SPRINTF_H_USES_VSNPRINTF
+namespace mozilla {
+namespace detail {
+
+struct MOZ_STACK_CLASS SprintfAppend final : public mozilla::PrintfTarget {
+  template <size_t N>
+  explicit SprintfAppend(char (&aBuf)[N]) : mBuf(aBuf), mBufLen(N) {}
+
+  bool append(const char* aStr, size_t aLen) override {
+    if (aLen == 0) {
+      return true;
+    }
+    // Don't copy more than what's left to use.
+    size_t copy = std::min(mBufLen, aLen);
+    if (copy > 0) {
+      memcpy(mBuf, aStr, copy);
+      mBuf += copy;
+      mBufLen -= copy;
+    }
+    return true;
+  }
+
+ private:
+  char* mBuf;
+  size_t mBufLen;
+};
+
+}  // namespace detail
+}  // namespace mozilla
+#  endif  // SPRINTF_H_USES_VSNPRINTF
+
 template <size_t N>
 MOZ_FORMAT_PRINTF(2, 0)
 int VsprintfLiteral(char (&buffer)[N], const char* format, va_list args) {
   MOZ_ASSERT(format != buffer);
+#  ifdef SPRINTF_H_USES_VSNPRINTF
   int result = vsnprintf(buffer, N, format, args);
   buffer[N - 1] = '\0';
   return result;
+#  else
+  mozilla::detail::SprintfAppend ss(buffer);
+  ss.vprint(format, args);
+  size_t len = ss.emitted();
+  buffer[std::min(len, N - 1)] = '\0';
+  return len;
+#  endif
 }
 
 template <size_t N>
diff --git a/toolkit/mozapps/update/updater/updater-common.build b/toolkit/mozapps/update/updater/updater-common.build
index 2f2a210f255b..28cf32982a4f 100644
--- a/toolkit/mozapps/update/updater/updater-common.build
+++ b/toolkit/mozapps/update/updater/updater-common.build
@@ -85,6 +85,7 @@ if CONFIG["MOZ_TSAN"]:
         "TsanOptions.cpp",
     ]
 
+DEFINES["SPRINTF_H_USES_VSNPRINTF"] = True
 DEFINES["NS_NO_XPCOM"] = True
 DisableStlWrapping()
 for var in ("MAR_CHANNEL_ID", "MOZ_APP_VERSION"):
diff --git a/xpcom/tests/moz.build b/xpcom/tests/moz.build
index e05fe9093d91..4758c655ace1 100644
--- a/xpcom/tests/moz.build
+++ b/xpcom/tests/moz.build
@@ -24,7 +24,7 @@ test_progs = [
 ]
 SimplePrograms(test_progs)
 
-USE_LIBS += ["mfbt"]
+USE_LIBS += ["mozglue"]
 
 XPCSHELL_TESTS_MANIFESTS += ["unit/xpcshell.ini"]