diff --git a/compiler-rt/lib/builtins/divdc3.c b/compiler-rt/lib/builtins/divdc3.c
--- a/compiler-rt/lib/builtins/divdc3.c
+++ b/compiler-rt/lib/builtins/divdc3.c
@@ -20,17 +20,19 @@
 COMPILER_RT_ABI Dcomplex __divdc3(double __a, double __b, double __c,
                                   double __d) {
   int __ilogbw = 0;
-  double __logbw = __compiler_rt_logb(crt_fmax(crt_fabs(__c), crt_fabs(__d)));
+  double __logbw = __compiler_rt_logb(__compiler_rt_fmax(crt_fabs(__c),
+                                                         crt_fabs(__d)));
   if (crt_isfinite(__logbw)) {
     __ilogbw = (int)__logbw;
-    __c = crt_scalbn(__c, -__ilogbw);
-    __d = crt_scalbn(__d, -__ilogbw);
+    __c = __compiler_rt_scalbn(__c, -__ilogbw);
+    __d = __compiler_rt_scalbn(__d, -__ilogbw);
   }
   double __denom = __c * __c + __d * __d;
   Dcomplex z;
-  COMPLEX_REAL(z) = crt_scalbn((__a * __c + __b * __d) / __denom, -__ilogbw);
+  COMPLEX_REAL(z) =
+      __compiler_rt_scalbn((__a * __c + __b * __d) / __denom, -__ilogbw);
   COMPLEX_IMAGINARY(z) =
-      crt_scalbn((__b * __c - __a * __d) / __denom, -__ilogbw);
+      __compiler_rt_scalbn((__b * __c - __a * __d) / __denom, -__ilogbw);
   if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z))) {
     if ((__denom == 0.0) && (!crt_isnan(__a) || !crt_isnan(__b))) {
       COMPLEX_REAL(z) = crt_copysign(CRT_INFINITY, __c) * __a;
diff --git a/compiler-rt/lib/builtins/divsc3.c b/compiler-rt/lib/builtins/divsc3.c
--- a/compiler-rt/lib/builtins/divsc3.c
+++ b/compiler-rt/lib/builtins/divsc3.c
@@ -20,17 +20,18 @@
 COMPILER_RT_ABI Fcomplex __divsc3(float __a, float __b, float __c, float __d) {
   int __ilogbw = 0;
   float __logbw =
-      __compiler_rt_logbf(crt_fmaxf(crt_fabsf(__c), crt_fabsf(__d)));
+      __compiler_rt_logbf(__compiler_rt_fmaxf(crt_fabsf(__c), crt_fabsf(__d)));
   if (crt_isfinite(__logbw)) {
     __ilogbw = (int)__logbw;
-    __c = crt_scalbnf(__c, -__ilogbw);
-    __d = crt_scalbnf(__d, -__ilogbw);
+    __c = __compiler_rt_scalbnf(__c, -__ilogbw);
+    __d = __compiler_rt_scalbnf(__d, -__ilogbw);
   }
   float __denom = __c * __c + __d * __d;
   Fcomplex z;
-  COMPLEX_REAL(z) = crt_scalbnf((__a * __c + __b * __d) / __denom, -__ilogbw);
+  COMPLEX_REAL(z) =
+      __compiler_rt_scalbnf((__a * __c + __b * __d) / __denom, -__ilogbw);
   COMPLEX_IMAGINARY(z) =
-      crt_scalbnf((__b * __c - __a * __d) / __denom, -__ilogbw);
+      __compiler_rt_scalbnf((__b * __c - __a * __d) / __denom, -__ilogbw);
   if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z))) {
     if ((__denom == 0) && (!crt_isnan(__a) || !crt_isnan(__b))) {
       COMPLEX_REAL(z) = crt_copysignf(CRT_INFINITY, __c) * __a;
diff --git a/compiler-rt/lib/builtins/divtc3.c b/compiler-rt/lib/builtins/divtc3.c
--- a/compiler-rt/lib/builtins/divtc3.c
+++ b/compiler-rt/lib/builtins/divtc3.c
@@ -21,17 +21,18 @@
                                   long double __c, long double __d) {
   int __ilogbw = 0;
   long double __logbw =
-      __compiler_rt_logbl(crt_fmaxl(crt_fabsl(__c), crt_fabsl(__d)));
+      __compiler_rt_logbl(__compiler_rt_fmaxl(crt_fabsl(__c), crt_fabsl(__d)));
   if (crt_isfinite(__logbw)) {
     __ilogbw = (int)__logbw;
-    __c = crt_scalbnl(__c, -__ilogbw);
-    __d = crt_scalbnl(__d, -__ilogbw);
+    __c = __compiler_rt_scalbnl(__c, -__ilogbw);
+    __d = __compiler_rt_scalbnl(__d, -__ilogbw);
   }
   long double __denom = __c * __c + __d * __d;
   Lcomplex z;
-  COMPLEX_REAL(z) = crt_scalbnl((__a * __c + __b * __d) / __denom, -__ilogbw);
+  COMPLEX_REAL(z) =
+      __compiler_rt_scalbnl((__a * __c + __b * __d) / __denom, -__ilogbw);
   COMPLEX_IMAGINARY(z) =
-      crt_scalbnl((__b * __c - __a * __d) / __denom, -__ilogbw);
+      __compiler_rt_scalbnl((__b * __c - __a * __d) / __denom, -__ilogbw);
   if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z))) {
     if ((__denom == 0.0) && (!crt_isnan(__a) || !crt_isnan(__b))) {
       COMPLEX_REAL(z) = crt_copysignl(CRT_INFINITY, __c) * __a;
diff --git a/compiler-rt/lib/builtins/fp_lib.h b/compiler-rt/lib/builtins/fp_lib.h
--- a/compiler-rt/lib/builtins/fp_lib.h
+++ b/compiler-rt/lib/builtins/fp_lib.h
@@ -299,28 +299,119 @@
     return exp - exponentBias - shift; // Unbias exponent
   }
 }
+
+// Avoid using scalbn from libm. Unlike libc/libm scalbn, this function never
+// sets errno on underflow/overflow.
+static __inline fp_t __compiler_rt_scalbnX(fp_t a, int b) {
+  const rep_t rep = toRep(a);
+  int exp = (rep & exponentMask) >> significandBits;
+
+  if (a == 0.0 || exp == maxExponent)
+    return a; // 0.0, NaN, or inf: return input
+
+  // Normalize subnormal input.
+  rep_t sig = rep & significandMask;
+  if (exp == 0) {
+    exp += normalize(&sig);
+    sig &= ~implicitBit; // clear the implicit bit again
+  }
+
+  if (__builtin_sadd_overflow(exp, b, &exp)) {
+    // Saturate the exponent, which will guarantee an underflow/overflow below.
+    exp = (b >= 0) ? INT_MAX : INT_MIN;
+  }
+
+  // Return this value: [+/-] 1.sig * 2 ** (exp - exponentBias).
+  const rep_t sign = rep & signBit;
+  if (exp >= maxExponent) {
+    // Overflow, which could produce infinity or the largest-magnitude value,
+    // depending on the rounding mode.
+    return fromRep(sign | ((rep_t)(maxExponent - 1) << significandBits)) * 2.0f;
+  } else if (exp <= 0) {
+    // Subnormal or underflow. Use floating-point multiply to handle truncation
+    // correctly.
+    fp_t tmp = fromRep(sign | (REP_C(1) << significandBits) | sig);
+    exp += exponentBias - 1;
+    if (exp < 1)
+      exp = 1;
+    tmp *= fromRep((rep_t)exp << significandBits);
+    return tmp;
+  } else
+    return fromRep(sign | ((rep_t)exp << significandBits) | sig);
+}
+
+// Avoid using fmax from libm.
+static __inline fp_t __compiler_rt_fmaxX(fp_t a, fp_t b) {
+  // If either argument is NaN, return the other argument. If both are NaN,
+  // arbitrarily return the second one. Otherwise, if both arguments are +/-0,
+  // arbitrarily return the first one.
+  return (crt_isnan(a) || a < b) ? b : a;
+}
+
 #endif
 
 #if defined(SINGLE_PRECISION)
+
 static __inline fp_t __compiler_rt_logbf(fp_t x) {
   return __compiler_rt_logbX(x);
 }
+static __inline fp_t __compiler_rt_scalbnf(fp_t a, int b) {
+  return __compiler_rt_scalbnX(a, b);
+}
+static __inline fp_t __compiler_rt_fmaxf(fp_t a, fp_t b) {
+#if defined(__aarch64__)
+  // Use __builtin_fmaxf which turns into an fmaxnm instruction on AArch64.
+  return __builtin_fmaxf(a, b);
+#else
+  // __builtin_fmaxf frequently turns into a libm call, so inline the function.
+  return __compiler_rt_fmaxX(a, b);
+#endif
+}
+
 #elif defined(DOUBLE_PRECISION)
+
 static __inline fp_t __compiler_rt_logb(fp_t x) {
   return __compiler_rt_logbX(x);
 }
+static __inline fp_t __compiler_rt_scalbn(fp_t a, int b) {
+  return __compiler_rt_scalbnX(a, b);
+}
+static __inline fp_t __compiler_rt_fmax(fp_t a, fp_t b) {
+#if defined(__aarch64__)
+  // Use __builtin_fmax which turns into an fmaxnm instruction on AArch64.
+  return __builtin_fmax(a, b);
+#else
+  // __builtin_fmax frequently turns into a libm call, so inline the function.
+  return __compiler_rt_fmaxX(a, b);
+#endif
+}
+
 #elif defined(QUAD_PRECISION)
+
 #if defined(CRT_LDBL_128BIT)
 static __inline fp_t __compiler_rt_logbl(fp_t x) {
   return __compiler_rt_logbX(x);
 }
+static __inline fp_t __compiler_rt_scalbnl(fp_t a, int b) {
+  return __compiler_rt_scalbnX(a, b);
+}
+static __inline fp_t __compiler_rt_fmaxl(fp_t a, fp_t b) {
+  return __compiler_rt_fmaxX(a, b);
+}
 #else
 // The generic implementation only works for ieee754 floating point. For other
 // floating point types, continue to rely on the libm implementation for now.
 static __inline long double __compiler_rt_logbl(long double x) {
   return crt_logbl(x);
 }
-#endif
-#endif
+static __inline long double __compiler_rt_scalbnl(long double a, int b) {
+  return crt_scalbnl(a, b);
+}
+static __inline long double __compiler_rt_fmaxl(long double a, long double b) {
+  return crt_fmaxl(a, b);
+}
+#endif // CRT_LDBL_128BIT
+
+#endif // *_PRECISION
 
 #endif // FP_LIB_HEADER
diff --git a/compiler-rt/lib/builtins/int_lib.h b/compiler-rt/lib/builtins/int_lib.h
--- a/compiler-rt/lib/builtins/int_lib.h
+++ b/compiler-rt/lib/builtins/int_lib.h
@@ -144,6 +144,19 @@
 #endif
 
 #define __builtin_clzl __builtin_clzll
+
+bool __inline __builtin_sadd_overflow(int x, int y, int *result) {
+  if ((x < 0) != (y < 0)) {
+    *result = x + y;
+    return false;
+  }
+  int tmp = (unsigned int)x + (unsigned int)y;
+  if ((tmp < 0) != (x < 0))
+    return true;
+  *result = tmp;
+  return false;
+}
+
 #endif // defined(_MSC_VER) && !defined(__clang__)
 
 #endif // INT_LIB_H
diff --git a/compiler-rt/lib/builtins/int_math.h b/compiler-rt/lib/builtins/int_math.h
--- a/compiler-rt/lib/builtins/int_math.h
+++ b/compiler-rt/lib/builtins/int_math.h
@@ -78,12 +78,8 @@
 #endif
 
 #if defined(_MSC_VER) && !defined(__clang__)
-#define crt_fmax(x, y) __max((x), (y))
-#define crt_fmaxf(x, y) __max((x), (y))
 #define crt_fmaxl(x, y) __max((x), (y))
 #else
-#define crt_fmax(x, y) __builtin_fmax((x), (y))
-#define crt_fmaxf(x, y) __builtin_fmaxf((x), (y))
 #define crt_fmaxl(x, y) __builtin_fmaxl((x), (y))
 #endif
 
@@ -94,12 +90,8 @@
 #endif
 
 #if defined(_MSC_VER) && !defined(__clang__)
-#define crt_scalbn(x, y) scalbn((x), (y))
-#define crt_scalbnf(x, y) scalbnf((x), (y))
 #define crt_scalbnl(x, y) scalbnl((x), (y))
 #else
-#define crt_scalbn(x, y) __builtin_scalbn((x), (y))
-#define crt_scalbnf(x, y) __builtin_scalbnf((x), (y))
 #define crt_scalbnl(x, y) __builtin_scalbnl((x), (y))
 #endif
 
diff --git a/compiler-rt/lib/builtins/ppc/divtc3.c b/compiler-rt/lib/builtins/ppc/divtc3.c
--- a/compiler-rt/lib/builtins/ppc/divtc3.c
+++ b/compiler-rt/lib/builtins/ppc/divtc3.c
@@ -27,15 +27,16 @@
 
   int ilogbw = 0;
   const double logbw =
-      __compiler_rt_logb(crt_fmax(crt_fabs(cDD.s.hi), crt_fabs(dDD.s.hi)));
+      __compiler_rt_logb(__compiler_rt_fmax(crt_fabs(cDD.s.hi),
+                                            crt_fabs(dDD.s.hi)));
 
   if (crt_isfinite(logbw)) {
     ilogbw = (int)logbw;
 
-    cDD.s.hi = crt_scalbn(cDD.s.hi, -ilogbw);
-    cDD.s.lo = crt_scalbn(cDD.s.lo, -ilogbw);
-    dDD.s.hi = crt_scalbn(dDD.s.hi, -ilogbw);
-    dDD.s.lo = crt_scalbn(dDD.s.lo, -ilogbw);
+    cDD.s.hi = __compiler_rt_scalbn(cDD.s.hi, -ilogbw);
+    cDD.s.lo = __compiler_rt_scalbn(cDD.s.lo, -ilogbw);
+    dDD.s.hi = __compiler_rt_scalbn(dDD.s.hi, -ilogbw);
+    dDD.s.lo = __compiler_rt_scalbn(dDD.s.lo, -ilogbw);
   }
 
   const long double denom =
@@ -48,10 +49,10 @@
   DD real = {.ld = __gcc_qdiv(realNumerator, denom)};
   DD imag = {.ld = __gcc_qdiv(imagNumerator, denom)};
 
-  real.s.hi = crt_scalbn(real.s.hi, -ilogbw);
-  real.s.lo = crt_scalbn(real.s.lo, -ilogbw);
-  imag.s.hi = crt_scalbn(imag.s.hi, -ilogbw);
-  imag.s.lo = crt_scalbn(imag.s.lo, -ilogbw);
+  real.s.hi = __compiler_rt_scalbn(real.s.hi, -ilogbw);
+  real.s.lo = __compiler_rt_scalbn(real.s.lo, -ilogbw);
+  imag.s.hi = __compiler_rt_scalbn(imag.s.hi, -ilogbw);
+  imag.s.lo = __compiler_rt_scalbn(imag.s.lo, -ilogbw);
 
   if (crt_isnan(real.s.hi) && crt_isnan(imag.s.hi)) {
     DD aDD = {.ld = a};
diff --git a/compiler-rt/test/builtins/Unit/compiler_rt_fmax_test.c b/compiler-rt/test/builtins/Unit/compiler_rt_fmax_test.c
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/builtins/Unit/compiler_rt_fmax_test.c
@@ -0,0 +1,41 @@
+// RUN: %clang_builtins %s %librt -o %t && %run %t
+
+#define DOUBLE_PRECISION
+#include <fenv.h>
+#include <math.h>
+#include <stdio.h>
+#include "fp_lib.h"
+
+int test__compiler_rt_fmax(fp_t x, fp_t y) {
+  fp_t crt_value = __compiler_rt_fmax(x, y);
+  fp_t libm_value = fmax(x, y);
+  // Consider +0 and -0 equal, and also disregard the sign/payload of two NaNs.
+  if (crt_value != libm_value &&
+      !(crt_isnan(crt_value) && crt_isnan(libm_value))) {
+    printf("error: in __compiler_rt_fmax(%a [%llX], %a [%llX]) = %a [%llX] "
+           "!= %a [%llX]\n",
+           x, (unsigned long long)toRep(x),
+           y, (unsigned long long)toRep(y),
+           crt_value, (unsigned long long)toRep(crt_value),
+           libm_value, (unsigned long long)toRep(libm_value));
+    return 1;
+  }
+  return 0;
+}
+
+fp_t cases[] = {
+  -NAN, NAN, -INFINITY, INFINITY, -0.0, 0.0, -1, 1, -2, 2,
+  -0x1.0p-1023, 0x1.0p-1023, -0x1.0p-1024, 0x1.0p-1024, // subnormals
+  -1.001, 1.001, -1.002, 1.002,
+};
+
+int main() {
+  const unsigned N = sizeof(cases) / sizeof(cases[0]);
+  unsigned i, j;
+  for (i = 0; i < N; ++i) {
+    for (j = 0; j < N; ++j) {
+      if (test__compiler_rt_fmax(cases[i], cases[j])) return 1;
+    }
+  }
+  return 0;
+}
diff --git a/compiler-rt/test/builtins/Unit/compiler_rt_fmaxf_test.c b/compiler-rt/test/builtins/Unit/compiler_rt_fmaxf_test.c
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/builtins/Unit/compiler_rt_fmaxf_test.c
@@ -0,0 +1,39 @@
+// RUN: %clang_builtins %s %librt -o %t && %run %t
+
+#define SINGLE_PRECISION
+#include <fenv.h>
+#include <math.h>
+#include <stdio.h>
+#include "fp_lib.h"
+
+int test__compiler_rt_fmaxf(fp_t x, fp_t y) {
+  fp_t crt_value = __compiler_rt_fmaxf(x, y);
+  fp_t libm_value = fmaxf(x, y);
+  // Consider +0 and -0 equal, and also disregard the sign/payload of two NaNs.
+  if (crt_value != libm_value &&
+      !(crt_isnan(crt_value) && crt_isnan(libm_value))) {
+    printf("error: in __compiler_rt_fmaxf(%a [%X], %a [%X]) = %a [%X] "
+           "!= %a [%X]\n",
+           x, toRep(x), y, toRep(y), crt_value, toRep(crt_value), libm_value,
+           toRep(libm_value));
+    return 1;
+  }
+  return 0;
+}
+
+fp_t cases[] = {
+  -NAN, NAN, -INFINITY, INFINITY, -0.0, 0.0, -1, 1, -2, 2,
+  -0x1.0p-127, 0x1.0p-127, -0x1.0p-128, 0x1.0p-128, // subnormals
+  -1.001, 1.001, -1.002, 1.002,
+};
+
+int main() {
+  const unsigned N = sizeof(cases) / sizeof(cases[0]);
+  unsigned i, j;
+  for (i = 0; i < N; ++i) {
+    for (j = 0; j < N; ++j) {
+      if (test__compiler_rt_fmaxf(cases[i], cases[j])) return 1;
+    }
+  }
+  return 0;
+}
diff --git a/compiler-rt/test/builtins/Unit/compiler_rt_fmaxl_test.c b/compiler-rt/test/builtins/Unit/compiler_rt_fmaxl_test.c
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/builtins/Unit/compiler_rt_fmaxl_test.c
@@ -0,0 +1,58 @@
+// RUN: %clang_builtins %s %librt -o %t && %run %t
+
+#define QUAD_PRECISION
+#include <fenv.h>
+#include <math.h>
+#include <stdio.h>
+#include "fp_lib.h"
+
+#if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
+
+int test__compiler_rt_fmaxl(fp_t x, fp_t y) {
+  fp_t crt_value = __compiler_rt_fmaxl(x, y);
+  fp_t libm_value = fmaxl(x, y);
+  // Consider +0 and -0 equal, and also disregard the sign/payload of two NaNs.
+  if (crt_value != libm_value &&
+      !(crt_isnan(crt_value) && crt_isnan(libm_value))) {
+    // Split expected values into two for printf
+    twords x_t, y_t, crt_value_t, libm_value_t;
+    x_t.all = toRep(x);
+    y_t.all = toRep(y);
+    crt_value_t.all = toRep(crt_value);
+    libm_value_t.all = toRep(libm_value);
+    printf(
+        "error: in __compiler_rt_fmaxl([%llX %llX], [%llX %llX]) = "
+        "[%llX %llX] != [%llX %llX]\n",
+        (unsigned long long)x_t.s.high, (unsigned long long)x_t.s.low,
+        (unsigned long long)y_t.s.high, (unsigned long long)y_t.s.low,
+        (unsigned long long)crt_value_t.s.high,
+        (unsigned long long)crt_value_t.s.low,
+        (unsigned long long)libm_value_t.s.high,
+        (unsigned long long)libm_value_t.s.low);
+    return 1;
+  }
+  return 0;
+}
+
+fp_t cases[] = {
+  -NAN, NAN, -INFINITY, INFINITY, -0.0, 0.0, -1, 1, -2, 2,
+  -0x1.0p-16383L, 0x1.0p-16383L, -0x1.0p-16384L, 0x1.0p-16384L, // subnormals
+  -1.001, 1.001, -1.002, 1.002,
+};
+
+#endif
+
+int main() {
+#if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
+  const unsigned N = sizeof(cases) / sizeof(cases[0]);
+  unsigned i, j;
+  for (i = 0; i < N; ++i) {
+    for (j = 0; j < N; ++j) {
+      if (test__compiler_rt_fmaxl(cases[i], cases[j])) return 1;
+    }
+  }
+#else
+  printf("skipped\n");
+#endif
+  return 0;
+}
diff --git a/compiler-rt/test/builtins/Unit/compiler_rt_scalbn_test.c b/compiler-rt/test/builtins/Unit/compiler_rt_scalbn_test.c
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/builtins/Unit/compiler_rt_scalbn_test.c
@@ -0,0 +1,74 @@
+// RUN: %clang_builtins %s %librt -o %t && %run %t
+
+#define DOUBLE_PRECISION
+#include <fenv.h>
+#include <float.h>
+#include <limits.h>
+#include <math.h>
+#include <stdio.h>
+#include "fp_lib.h"
+
+int test__compiler_rt_scalbn(const char *mode, fp_t x, int y) {
+  fp_t crt_value = __compiler_rt_scalbn(x, y);
+  fp_t libm_value = scalbn(x, y);
+  // Consider +/-0 unequal, but disregard the sign/payload of NaN.
+  if (toRep(crt_value) != toRep(libm_value) &&
+      !(crt_isnan(crt_value) && crt_isnan(libm_value))) {
+    printf("error: [%s] in __compiler_rt_scalbn(%a [%llX], %d) = %a [%llX] "
+           "!= %a [%llX]\n",
+           mode, x, (unsigned long long)toRep(x), y,
+           crt_value, (unsigned long long)toRep(crt_value),
+           libm_value, (unsigned long long)toRep(libm_value));
+    return 1;
+  }
+  return 0;
+}
+
+fp_t cases[] = {
+  -NAN, NAN, -INFINITY, INFINITY, -0.0, 0.0, -1, 1, -2, 2,
+  DBL_TRUE_MIN, DBL_MIN, DBL_MAX,
+  -1.001, 1.001, -1.002, 1.002, 1.e-6, -1.e-6,
+  0x1.0p-1021,
+  0x1.0p-1022,
+  0x1.0p-1023, // subnormal
+  0x1.0p-1024, // subnormal
+};
+
+int iterate_cases(const char *mode) {
+  const unsigned N = sizeof(cases) / sizeof(cases[0]);
+  unsigned i;
+  for (i = 0; i < N; ++i) {
+    int j;
+    for (j = -5; j <= 5; ++j) {
+      if (test__compiler_rt_scalbn(mode, cases[i], j)) return 1;
+    }
+    if (test__compiler_rt_scalbn(mode, cases[i], -10000)) return 1;
+    if (test__compiler_rt_scalbn(mode, cases[i], 10000)) return 1;
+    if (test__compiler_rt_scalbn(mode, cases[i], INT_MIN)) return 1;
+    if (test__compiler_rt_scalbn(mode, cases[i], INT_MAX)) return 1;
+  }
+  return 0;
+}
+
+int main() {
+  if (iterate_cases("default")) return 1;
+
+  // Rounding mode tests on supported architectures. __compiler_rt_scalbn
+  // should have the same rounding behavior as double-precision multiplication.
+#if (defined(__arm__) || defined(__aarch64__)) && defined(__ARM_FP) || \
+    defined(__i386__) || defined(__x86_64__)
+  fesetround(FE_UPWARD);
+  if (iterate_cases("FE_UPWARD")) return 1;
+
+  fesetround(FE_DOWNWARD);
+  if (iterate_cases("FE_DOWNWARD")) return 1;
+
+  fesetround(FE_TOWARDZERO);
+  if (iterate_cases("FE_TOWARDZERO")) return 1;
+
+  fesetround(FE_TONEAREST);
+  if (iterate_cases("FE_TONEAREST")) return 1;
+#endif
+
+  return 0;
+}
diff --git a/compiler-rt/test/builtins/Unit/compiler_rt_scalbnf_test.c b/compiler-rt/test/builtins/Unit/compiler_rt_scalbnf_test.c
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/builtins/Unit/compiler_rt_scalbnf_test.c
@@ -0,0 +1,73 @@
+// RUN: %clang_builtins %s %librt -o %t && %run %t
+
+#define SINGLE_PRECISION
+#include <fenv.h>
+#include <float.h>
+#include <limits.h>
+#include <math.h>
+#include <stdio.h>
+#include "fp_lib.h"
+
+int test__compiler_rt_scalbnf(const char *mode, fp_t x, int y) {
+  fp_t crt_value = __compiler_rt_scalbnf(x, y);
+  fp_t libm_value = scalbnf(x, y);
+  // Consider +/-0 unequal, but disregard the sign/payload of NaN.
+  if (toRep(crt_value) != toRep(libm_value) &&
+      !(crt_isnan(crt_value) && crt_isnan(libm_value))) {
+    printf("error: [%s] in __compiler_rt_scalbnf(%a [%X], %d) = %a [%X] "
+           "!= %a [%X]\n",
+           mode, x, toRep(x), y, crt_value, toRep(crt_value),
+           libm_value, toRep(libm_value));
+    return 1;
+  }
+  return 0;
+}
+
+fp_t cases[] = {
+  -NAN, NAN, -INFINITY, INFINITY, -0.0, 0.0, -1, 1, -2, 2,
+  FLT_TRUE_MIN, FLT_MIN, FLT_MAX,
+  -1.001, 1.001, -1.002, 1.002, 1.e-6, -1.e-6,
+  0x1.0p-125,
+  0x1.0p-126,
+  0x1.0p-127, // subnormal
+  0x1.0p-128, // subnormal
+};
+
+int iterate_cases(const char *mode) {
+  const unsigned N = sizeof(cases) / sizeof(cases[0]);
+  unsigned i;
+  for (i = 0; i < N; ++i) {
+    int j;
+    for (j = -5; j <= 5; ++j) {
+      if (test__compiler_rt_scalbnf(mode, cases[i], j)) return 1;
+    }
+    if (test__compiler_rt_scalbnf(mode, cases[i], -1000)) return 1;
+    if (test__compiler_rt_scalbnf(mode, cases[i], 1000)) return 1;
+    if (test__compiler_rt_scalbnf(mode, cases[i], INT_MIN)) return 1;
+    if (test__compiler_rt_scalbnf(mode, cases[i], INT_MAX)) return 1;
+  }
+  return 0;
+}
+
+int main() {
+  if (iterate_cases("default")) return 1;
+
+  // Rounding mode tests on supported architectures. __compiler_rt_scalbnf
+  // should have the same rounding behavior as single-precision multiplication.
+#if (defined(__arm__) || defined(__aarch64__)) && defined(__ARM_FP) || \
+    defined(__i386__) || defined(__x86_64__)
+  fesetround(FE_UPWARD);
+  if (iterate_cases("FE_UPWARD")) return 1;
+
+  fesetround(FE_DOWNWARD);
+  if (iterate_cases("FE_DOWNWARD")) return 1;
+
+  fesetround(FE_TOWARDZERO);
+  if (iterate_cases("FE_TOWARDZERO")) return 1;
+
+  fesetround(FE_TONEAREST);
+  if (iterate_cases("FE_TONEAREST")) return 1;
+#endif
+
+  return 0;
+}
diff --git a/compiler-rt/test/builtins/Unit/compiler_rt_scalbnl_test.c b/compiler-rt/test/builtins/Unit/compiler_rt_scalbnl_test.c
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/builtins/Unit/compiler_rt_scalbnl_test.c
@@ -0,0 +1,77 @@
+// RUN: %clang_builtins %s %librt -o %t && %run %t
+
+#define QUAD_PRECISION
+#include <fenv.h>
+#include <float.h>
+#include <limits.h>
+#include <math.h>
+#include <stdio.h>
+#include "fp_lib.h"
+
+#if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
+
+int test__compiler_rt_scalbnl(const char *mode, fp_t x, int y) {
+  fp_t crt_value = __compiler_rt_scalbnl(x, y);
+  fp_t libm_value = scalbnl(x, y);
+  // Consider +/-0 unequal, but disregard the sign/payload of NaN.
+  if (toRep(crt_value) != toRep(libm_value) &&
+      !(crt_isnan(crt_value) && crt_isnan(libm_value))) {
+    // Split expected values into two for printf
+    twords x_t, crt_value_t, libm_value_t;
+    x_t.all = toRep(x);
+    crt_value_t.all = toRep(crt_value);
+    libm_value_t.all = toRep(libm_value);
+    printf(
+        "error: [%s] in __compiler_rt_scalbnl([%llX %llX], %d) = "
+        "[%llX %llX] != [%llX %llX]\n",
+        mode, (unsigned long long)x_t.s.high, (unsigned long long)x_t.s.low, y,
+        (unsigned long long)crt_value_t.s.high,
+        (unsigned long long)crt_value_t.s.low,
+        (unsigned long long)libm_value_t.s.high,
+        (unsigned long long)libm_value_t.s.low);
+    return 1;
+  }
+  return 0;
+}
+
+fp_t cases[] = {
+  -NAN, NAN, -INFINITY, INFINITY, -0.0, 0.0, -1, 1, -2, 2,
+  LDBL_TRUE_MIN, LDBL_MIN, LDBL_MAX,
+  -1.001, 1.001, -1.002, 1.002, 1.e-6, -1.e-6,
+  0x1.0p-16381L,
+  0x1.0p-16382L,
+  0x1.0p-16383L, // subnormal
+  0x1.0p-16384L, // subnormal
+};
+
+int iterate_cases(const char *mode) {
+  const unsigned N = sizeof(cases) / sizeof(cases[0]);
+  unsigned i;
+  for (i = 0; i < N; ++i) {
+    int j;
+    for (j = -5; j <= 5; ++j) {
+      if (test__compiler_rt_scalbnl(mode, cases[i], j)) return 1;
+    }
+    if (test__compiler_rt_scalbnl(mode, cases[i], -100000)) return 1;
+    if (test__compiler_rt_scalbnl(mode, cases[i], 100000)) return 1;
+    if (test__compiler_rt_scalbnl(mode, cases[i], INT_MIN)) return 1;
+    if (test__compiler_rt_scalbnl(mode, cases[i], INT_MAX)) return 1;
+  }
+  return 0;
+}
+
+#endif
+
+int main() {
+#if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
+  if (iterate_cases("default")) return 1;
+
+  // Skip rounding mode tests (fesetround) because compiler-rt's quad-precision
+  // multiply also ignores the current rounding mode.
+
+#else
+  printf("skipped\n");
+#endif
+
+  return 0;
+}